There are lots of different ways that card companies try to make money from providing pre-paid cards. Some charge quite a large fee to acquire the card, but are fairly cheap to use after that. Others work the other way round. Some are best for just occasional use. Others are better for heavy use. And so on . . .
To find out everything you need to know about how the cards work, read through the five pages of information starting here:
http://www.moneysupermarket.com/cards/prepaid- cards-guide1.asp
Then combine this list:
http://www.moneysupermarket.com/prepaidcards/C ardsResults.asp?feature=Prepaid&Type=CreditCar d
with this information:
http://www.moneysavingexpert.com/cards/prepaid -cards
to find what's best for you.
Chris