The lucky star with reasons to be cheerful

The first time I meet Sally Hawkins, on the set of Gurinder Chadha's supernatural farce It's a Wonderful Afterlife, she's playing a young, ditzy India-obsessed psychic, gamely going through a stage-packed Bollywood dance routine in a baby-doll-pink sari. She confides that they're under-rehearsed but Hawkins's infectious enthusiasm steals the show – even drenched in flying curry. "It's always good to throw yourself in," she sighs, "although on a day like today..."

Six months later, in remote Welsh countryside she's filming coming-of-age comedy Submarine, done up with a helmet-like hairdo as a frustrated middle-aged mother in a failing marriage.

Impressively, neither part even remotely recalls Hawkins's award-winning, breakout 2008 performance as sunny primary school teacher Poppy Cross in Mike Leigh's Happy-Go-Lucky. In person, it's Poppy's good-natured, unassuming warmth that seems closest to the pretty, petite 34-year-old, even her endearingly iffy puns.

"I've got red-eye and I came in on the red-eye," she jokes, exhausted at having flown in overnight from her current Broadway production of Shaw's Mrs Warren's Profession.

What's less evident at first glance is the steel and self-assuredness that Happy-Go-Lucky's buoyant Poppy gradually revealed. Indeed, if one reads some past interviews with Hawkins, there's a patronising tendency to tag her cripplingly shy, almost awkwardly bumbling off-screen; as if the one role she really hasn't yet nailed is herself.

As an actress, however, the only labels Hawkins has accrued are rave reviews and she's busier than ever. Today, London, last night Broadway, the week before, the Toronto Film Festival, where she had no less than three acclaimed films: Submarine (subject of a bidding war won by Harvey Weinstein); Oscar-tip Never Let Me Go, in which she has a cameo as a supportive teacher to doomed public school kids; and her starring role in another award-bait movie, Made in Dagenham, in which Hawkins leads a group of striking 1960s car factory women machinists fighting for a fair wage.

A kind of Estuary-based, feelgood Norma Rae, the film is based on the real-life female Ford employees whose protests helped bring about the Equal Pay Act. Hawkins's Rita, an amalgam of several Dagenham workers, is the linchpin for industrial action, though the gentle, likable film is political with a small "p". For Hawkins, this mirrors the women themselves, "who weren't political animals" and helps reflect sexual inequality across a wider context and timeframe.

"When you think how recently these women went through this, my God we've progressed," she points out. "But there's still so much to do." Apparently, Hawkins's own comfortable south London childhood – with her parents, renowned children's books authors Colin and Jacqui, and brother – resulted in quite a culture shock when she left home.

"I was brought up with a fantastically bright, strong-minded, independent mother," she says, "and quite shocked by how I was treated as a young woman. Even on the bus. And the subtler it is, the more undermining and dangerous it can be."

Take her own industry. "It's been male dominated for so long," she says sadly. "It's great that the first woman [director, Kathryn Bigelow] won the Oscar this year, but the first woman? Now? It's insane. I can count on one hand the amount of female directors I've worked with. But having said that, I think it is changing."

If there's one word that keep cropping up in Hawkins's descriptions of herself and her career, it's "lucky", whether it's her creative relationship with Mike Leigh, her New York stage stint ("I never thought I'd be on Broadway! 42nd Street's the first musical I ever saw!") or her tongue-in-cheek pact with good friend James Corden to get hitched if they're still both single at 35. "I think he's probably got a long list to get through before then, but I'd be a lucky lady if I married James Corden," she grins, simultaneously – and deftly – deflecting any revelations of her own relationship status.

Mention her surprise Golden Globe win for Happy-Go-Lucky, where she beat the likes of Emma Thompson and Meryl Streep, and she relives the shock, wide-eyed. "I was totally gobsmacked and I'd completely discounted it because I wasn't sitting in the winners' pit," she recounts. "I remember meeting Johnny Depp backstage but he was backing off as I told him how much I loved him – and this was in the dark so it's obviously a bit sinister. He was just trying to give me the envelope and leave but I wouldn't quite let him go..."

Perhaps it's this hesitancy and modesty that have marked Hawkins out in the press as somehow too meek and mild; and smacks of the same insinuating discrimination she's been outlining. She's a naturally private person, true, but decline to typecast her as a wallflower and she responds with forthrightness and a quick, playful wit, even on such difficult topics as the dyslexia that inhibited her as a child.

"I have to underline that some people are crippled with it and it was nothing like that," she asserts, "but I still panic when I sight-read. I need to have the text and almost know it by heart because otherwise I'll say something else entirely." She laughs heartily at the idea that such unplanned diversions might have appealed to the famously improvisational Mike Leigh.

"I don't find [publicity] easy and when you have someone who's difficult, it just clams me up," she explains. "I'll know that they want an easy interview to pigeonhole me, or for me to come out with these amazing soundbites. But I can't do that, I'm not that kind of person. And I don't want to be, really."

Still, exposing yourself off-screen is part of the job of acting on-screen, and one she recognises that she has to work harder at. "Like [Made in Dagenham's] Rita, you learn it on the hop," she says with a wide, accepting smile. "You're on your own and nobody tells you how to do it."

Nor does anyone, it seems, need to. Sally Hawkins is going places. She seems happy. She says she's lucky. But happy-go-lucky? Not this actress, a woman so hard working, so quietly clear about what she wants – and doesn't. Like Poppy Cross, like Rita O'Grady, underestimate her at your peril.

'Made in Dagenham' is out on 1 October; 'Never Let Me Go' opens the BFI London Film Festival on 13 October and goes on general release on 21 January 2011