Ok, this is particularly relevent for RyanAir - looking for flights for two of us to germany - card fees were £19! rip off. Now, both RyanAir and EasyJet offer no fees if you pay by visa electron. All good, but no-one has Visa Electron cards!
Well, the post office offer a pre-pay visa electron 'travel card'. You can apply online (didn't work for me) and get £1.55 quidco, or get it in your local post office if you need it quickly. Minimum top up is £50, they charge you 1.5% for a sterling card, minimum £3.
Once the card is activated (takes 24 hours), you can use it to get fee-free flights with RyanAir. You just have to make sure you've 'topped it up' beforehand. I've just used it for £90 and can confirm it workshttp://www.postoffice.co.uk/portal/po/jump1?catId=19300207&mediaId=26800661