Quirk ethic: Sally Phillips finally lands a lead role after 20 years of playing oddballs

Sally Phillips is anxious. Though it's not the sort of anxiousness that attended the making of her first film as a writer, the recent Brit indie The Decoy Bride. "Horrific!" she says, eyes agape and soul still raw, of the romcom which starred David Tennant and Kelly Macdonald. "It was like having every toenail pulled out – at every stage. And the pain just keeps coming." We'll come back to that.

And not anxiousness of the sort surrounding the off-on-off-again production of the third Bridget Jones movie. "They booked me [to shoot] last August," the actress-writer-comedian says of the producers behind the box-office-friendly franchise, in which she plays the hapless, wine-swilling singleton's pal Shazza. "That would have been difficult for me anyway cos I was pregnant. Then they lost the director," she adds, meaning Paul Feig, who made last year's hit American comedy Bridesmaids. "He walked because it was a shambles, apparently – this is all gossip," she adds hastily. We'll come back to those points, too.

No, Phillips is anxious because she's just finished filming the first sitcom in which she has the lead role. Parents centres on a businesswoman who loses her job, then her home, and has to move herself, her under-employed husband and their teenage children back into her parents' home. As credit-crunch comedies go, it's a good one.

After supporting roles in I'm Alan Partridge (giggly receptionist) and Miranda (braying chum), the ensemble comedies (Hippies, with Simon Pegg; Green Wing, with loads of people) and the sketch shows (three series of Smack the Pony, the pilot for Brass Eye), Phillips is front and centre. Though, unusually for her, she hasn't been involved in the writing.

"As a writer myself, my job has very often been to also write on the job. So you get the script and a vague idea of how the scene might work, and you then add funny words or change the script. I'm not the world's best writer or the world's best actor, but I can do that thing where I can fix – or ruin – fix-slash-ruin," she waffles, humility tumbling over candour and humour, "add quirk, add value..."

But with Parents, created by young newcomers Joe Tucker and Lloyd Woolf, "I didn't change anything at all. The writing seemed very good, very simple and very truthful."

And here's why she's anxious: I've seen the opening episode, Phillips hasn't. What, post-filming, might the editors, the eggheads and the commissioners at the channel – Sky One – done to it, she frets? After all, she recalls the anecdote a friend who worked on Channel 5's Family Affairs once recounted. A new producer was hired, and his opening gambit to the creators was eye-watering. "You know why this soap doesn't work? Cos everyone's fucking related and no one can fuck each other!" went his team-building pep-talk. "I want the family dead!"

"Then," smiles Phillips, Mr Conciliatory "left the room and half the writers started crying at the idea of killing off these characters they'd created."

I can reassure her that Parents features no infanticide – but perhaps an incest storyline could be developed down the line. "Yeah!" she beams. "That would make it edgy. Bit more BBC3."

That shouldn't be necessary. Or not till series three, at least. Parents is a broad family comedy, both funny and "now". It follows the travails of the Popes as they're forced to relocate from a nice house in affluent west London to Jenny Pope's cabbage-smelling parental home in Kettering. Phillips is great as Jenny, the one-time high-flier and breadwinner who loses her job after things get "punchy" at work – the hilarious flashbacks of her grappling with a colleague on the office floor offer a fine outlet for the physical humour skills Phillips learnt at clown school in her twenties. And fortysomething Jenny's turmoil as she's forced to wrestle with downsizing, job-hunting and relying once more on her parents is lightly and smartly of-the-moment.

"It also feels timely from a purely pragmatic view," she adds, "in that My Family is now finished, and Outnumbered is now on, what series is it – five, six? And their kids must be getting a bit old. So there isn't a British family sitcom at the moment.

"And Tom Conti is a genius, obviously." The veteran Scottish actor plays Jenny's twinkly father. "His is the classic does-nothing-to-maximum-effect performance," she says, and she means it as a compliment. "He said this brilliant thing on set: 'Acting's only difficult if you can't do it.'"

Sally Phillips is rattling round a huge lounge-cum-conference-room in the basement of a central London hotel. She's travelled in from Richmond in the south-west suburbs, where she lives with her Spanish husband and three young children. She's friendly, smiley and happy to prattle away – at my urging – in spoddy detail about the nuts and bolts of comedy. What she won't be discussing, as laid down by the Sky press office beforehand, is her religion (she's a practising Christian) or her seven-year-old son, who has Down's syndrome.

She's had 20-odd years in the biz, from early stand-up shows at the Edinburgh fringe, to working with multi-tasking comedy maestros Pegg, Chris Morris and Steve Coogan. She's also observed Bridget Jones's scriptwriter Richard Curtis at work, and Miranda Hart. In fact, on the way in this morning, the 42-year-old says she was thinking about her professional trajectory since graduating from Oxford with a degree in Italian.

"My career started off really abnormally, but I just seem to have got more and more normal!" Early on she was part of a troupe called Cluub [sic] Zarathustra, which she describes as "almost Weimar Republic cabaret". They appeared at the Edinburgh Festival Fringe and had a weekly residency in a London pub. Simon Munnery, Stuart Lee and the Mighty Boosh's Julian Barratt were also involved.

"Some shows would be amazing, the rest would be appalling, and the audience would all leave. That's where my heart was for a long time – that surreal kind of humour. I was 'the explainer', offering 15 minutes of post-structural analysis of one line Simon had just done. I did one sketch with Julian where he was the last man on earth, I was the last woman, but I refused to have sex with him. Or there was a foot-long inflatable penis that we pushed at the audience. Happy days! And now I'm doing a family sitcom..." she concludes with a glint of wryness.

"But that was just the graft of learning – writing 15 minutes of new material every week. I used to be insulted when people said I was an actress. Cos I thought as a comedian you had to write, and I prided myself on that."

One of her earliest regular TV jobs was a 1995 sketch show called Six Pairs of Pants, made by regional ITV channels Anglia and Meridian. Pegg also starred, as did his future Spaced partner Jessica Hynes. In 1999, Phillips and Pegg starred in the short-lived comedy Hippies. Set in an Oz-like 1960s magazine, it was written by Father Ted creators Graham Linehan and Arthur Matthews. "What I observed in Simon is that there are other comedy actors who can maybe do a character as well as him, and certainly can change more than he can. He uses the fact that he can't totally change utterly to his advantage. His personality is enormously charming, and that comes through. Which is the opposite to the Chris Morris school where the people..." Phillips stops. "Is this not really boring?"

No, I insist, it's interesting, not least because the brain behind The Day Today and Brass Eye is as elusive and mysterious a genius as they come. "OK, so the whole k skill for doing the Chris Morris thing is to be completely absent as a personality. So none of your personality comes through. You're literally a very credible puppet. So people such as Amelia Bullmore or Kevin Eldon do that better than Simon Pegg. But Simon's become a star because he can't do that. Being visible, people like it – the star- quality thing is not changing [for a role]."

What's her star quality? "I don't know that I have any star quality, do I?" she dimples. "If I had star quality, I might be a star."

Phillips – a star, in a small but bright, small-screen way, and impressively and pointedly straight-talking – was born in Hong Kong. She spent her childhood in 10 different countries courtesy of her dad's job with British Airways. An early memory is being evacuated from Beirut when she was five, her dad forced to stay behind to "close down operations". Sent to boarding school in England as a nine-year-old, she was 14 before her family returned to the UK full-time. Was she messed up by that turbulence of instability and absence?

"I don't know..." she begins. "When I started doing interviews and people would ask me about school, I would say it was horrific, I hated it, I got bullied, etc, etc. But I have to say I am now over it," she laughs. "I think... It makes you what you are. I wasn't comfortable, but I also think I styled myself as different. I didn't want to be the same as everybody else. But was that because I got bullied; or was it that I didn't want to be like everybody else?

"What was confusing," she continues, "was to have a certain identity overseas: being very English, which meant having tea at four o'clock and the World Service on 24 hours a day, a constant backdrop... Then to come back to England and feel different from everybody else who was sailing in the Cotswolds. I remember someone coming to our suburban house and saying, 'Where's your swimming pool?' It's quite confusing being one of the less wealthy people at a posh place."

Abroad, Phillips amplified her Englishness: niceness, kindness, never boasting, "all those characteristics of Britishness that I had absorbed, I don't know where from. I probably spoke like a 1950s newscaster."

But back in the UK, "Britishness seemed to be all about Smash Hits and, given that I was at a girls' boarding school, having Hobbs shoes and Benetton jumpers – and people being really very un-nice."

So was writing – and later acting – an escape?

"I definitely used to write a lot at school. Comic poetry and drawings about people. But the thing about being abroad is, you're an outsider looking in. And I don't think you can quite ever shake that. And comedy is a very natural place to be an observer. You reflect society back at itself, with exaggerated bits."

After soft-pedalling her career while she had children, Phillips is now busy in multiple directions. The third Bridget Jones film remains a going concern – as you might expect of a franchise that has already taken half-a-billion dollars – albeit still stuck in limbo. After The Full Monty director Peter Cattaneo was hired to replace Feig, production was scheduled to begin early this year. Then the lead actors queried the quality and readiness of the script.

"It was shelved. I think they had an option that they were going to have to pay £5m each to Hugh [Grant], Colin [Firth] and Renée [Zellweger] if they didn't officially cancel it. So they cancelled it – but we've been told it will happen at some point."

Then there's a new sketch show for Channel 4, and next month shooting finally begins on series three of Miranda. It's taken a while for Hart (who Phillips encouraged early in her career by introducing her to the producer of Smack the Pony and Green Wing, and suggesting she contact French and Saunders) to write. Why the delay?

"I don't know. You'd have to ask her." But it seems she does know. "I think it started as just Miranda mucking about, a bit of her stand-up. Then suddenly it got hailed as the funniest sitcom ever made. And how hard is it to write the third series of THE FUNNIEST SITCOM EVER MADE?" she blares, mimicking the hype. "It's impossible. Miranda is very funny but a quite-normal, down-to-earth person who I think probably got intimidated by the task in hand. But she's done it now."

Phillips is sympathetic, being well-versed in the traumas of writing. The Decoy Bride, she admits, was trying all round, even before it fizzled out at the box office. She had spotted a celebrity wedding in a celebrity magazine, and had the germ of an idea for a script. With a young family, writing a screenplay would enable her to stay home for a while.

"My biggest error was, I didn't really care that much about the story – it was just an idea. If I'd known it was going to take seven years and be that painful I would have written about something I really cared about. So then at least when it's terrible, you've expended all that energy on something you're interested in. But it's about a celebrity wedding – I care not a bit about that!"

She insists that she is still proud of the film – "it was not insincere" – and that her cast was great. "But if it had an extra 10 minutes and an extra £500,000 it would have been awful lot better."

Her budget was £2.5m, most of which came from CinemaNX, the film arm of the Isle of Man government. "But their money comes with a condition: you have to shoot there. And flights are not cheap to the Isle of Man. Once you've paid for that, and paid for Kelly and David and Alice Eve, you haven't got much left."

Did she make any money?

"No!" she hoots. "I came out with a massive loss. That's the other thing – it cost me money! I did about seven free rewrites. And the childcare alone..." she sighs.

Undaunted, Phillips has "several" other screenplays on her laptop, with "one or two" close to being goers. She also wants to write/present a documentary, and currently has a comedy script awaiting approval at the BBC. Like Parents, Stick or Twist is another timely idea, written for her and her old Smack the Pony colleagues Doon Mackichan and Fiona Allen, about three sisters whose marriages are in crisis. "It's an antidote to, or the opposite of, Mistresses," she explains. "If you tried to actually hang about in hotel bars and actually tried to have anonymous sex, what would really happen?"

Two Beeb executives like it, but seven months since she submitted the script, a third has yet to read it. "It's only 40 pages! How hard can it be?" But in any case, she snorts, a friend told her "BBC2 is full". Still, at least this time she didn't kill herself in the writing process. As with her turn in Parents, she was a lot more relaxed about the process.

"Cos I'm old now, I've had enough experience to be able to do it with less preparation. Whereas 20 years ago I would have needed all the time." Now, as a time-poor mother of three, "I can make a virtue of slapdash," she says with a grin. "Slapdash can give you courage."

But maybe, she concedes, she might have rushed back to acting from maternity leave a touch too fast. "I had a brand-new baby and I'm quite fat in some scenes in Parents – I'm very visibly a stone heavier sometimes. And also breastfeeding boobs!" she shrieks. "There was one scene where I was lying in bed, and the director was like, 'Why can't I see her face any more?'"

'Parents' starts on Sky One at 8.30pm on Friday. 'Decoy Bride' is available on DVD now