Halifax Clarity card is what I use. You pay interest only from when you withdraw money from ATM's which works out at around 1% per month. Nothing to stop you reducing that cost though by making early payments on the card.
Also Nationwide Flex plus seems to be totally free except you pay 10 pounds per month for the account. Some interest can be accrued on the first 2,500 pounds in the current account to offset this fee.