Hi
The prepaid Mastercard I have applied for is the Barclays FairFX card. My brother-in-law is a frequent flyer with Ryanair and did some research and this is the best one he found.
This is some info off the Money Saving website: Ryanair: To avoid payment fees with Ryanair, the prepaid card must be issued by Mastercard. The best is the FairFx* Anywhere card, where the only charge is 1.5% of the transaction amount each time you spend on it. If you use a debit card to top it up online or by the phone there's no charge.
It is free to apply for, but you have to pay £10.00 minimum (which is money put on your card to spend towards your first purchase). Where it says minimum £100, just change this to £10.00 - it does work, I did it.
They charge about 1.5% each time you use it, so still works out much cheaper than giving that cheeky Irish git your money!
To apply go to Fairfx.com and follow "apply now" tab. Under "select delivery method" press "New FairFX card". Make sure you do the one in pounds, not euros or dollars.
One you've applied you need to pay the £10 straight away, and you should get the card in around 10 days, my brother-in-law had he's in 5 days.
Their notes on fees: "We do not charge any monthly or quarterly fees or any fees for foreign exchange transactions, checking your on-line balance and statements or for purchase transactions. Please refer to your terms and conditions for detailed information regarding fees".
Any more questions, I'll do my best to help.
Rachel