Do the cheap flights you see advertised really exist?

How easy is it to get those bargain deals? That's what Kate Sanderson and the BBC's Watchdog team set out to discover. They set out to book flights from London to five European cities (Paris, Rome, Dublin, Amsterdam and Barcelona) departing after midday on Friday 26 April and returning after noon on Sunday 28 April.

* Ryanair offers to get you to Dublin for £9 one way. The small print says this applies to selected flights, which could explain why the cheapest deal the team could find totalled £106 return. Ryanair told Watchdog it has caused a low fares revolution for consumers and that its average ticket price is £35.

* Buzz advertises a £19 one-way flight to Paris. But Watchdog had no luck securing the deal and was quoted £118 return. Buzz said that it is cheaper than many airlines over a range of dates and destinations – not just the ones the programme had chosen.

* easyJet tells holidaymakers to book early and pay less. The team weren't sure how early you need to book to fly to Barcelona, but it's obviously longer than two weeks as there were no £32.50 single tickets available. A £175 return was offered instead; easyJet says it is all for consumers shopping around for the best deals.

* From Stansted to Rome, the team tried low-cost airline Go and found a return trip for £170 return – but Ryanair undercut this by £39.

* BMI's new no-frills airline , Bmibaby, charged £155 for a return from East Midlands to Dublin – not what many consumers would rate low cost. Bmibaby says it has many one-way flights for £25 or less.

The cheapest deals from London airports to five European cities

Dublin

The cheapest was Ryanair at £106 return (but not quite the £18 headline fare).

Rome

The lowest rate was offered by Ryanair at £141 return.

Barcelona

easyJet gave the best rate at £175 return (a long way from the £65 lead-in return fare).

Paris

Air France beat the low-cost competition, offering seats from Heathrow for £104 return.

Amsterdam

The cheapest return deal was with KLM at £125.

Top tips to get the best deals:

1. Plan ahead. You can sometimes snap up a last-minute bargain, but usually the later you leave it the more you pay.

2. Be flexible. Adjusting your departure time by a few hours can save a small fortune.

3. Travel on Tuesdays and Wednesdays – these are the days the airlines dread, when they're forced to slash fares to get bums on seats.

4. Within Europe, go online – these days, most UK airlines penalise passengers who don't book on the internet. But don't hit that "Buy now" button until you've checked every detail of the booking.

5. Heading down under? For long-haul flights, cut in the middle man – you'll usually pay less and get more with a specialist agent than booking direct with the airline.

6. Change planes to save cash – on flights to America or Asia, a connecting flight can cut hundreds from the fare – and you get to stretch your legs.

7. Check those dreaded "taxes, fees and charges" are included in the advertised fare – the law says they're supposed to be, but not everyone complies.

8. If you have to cancel, ask for those taxes, fees and charges back – even if your ticket says "non-refundable".

9. Before you snap up that no-frills flight, work out the cost of reaching the airport. Low-cost airlines often use airports that are awkward and expensive to reach. And add a fiver to cover inflight drinks and snacks.

10. The airline industry has a long tradition of milking the travelling public – make sure you know about all the extras, from "tickets on departure" to "security surcharge" before you book.

11. If you pay with a credit card you might be charged a fee – so if you can, use a debit card.

Visit www.bbc.co.uk/watchdog for more details of this and other travel topics