This may clarify a few things. As I said, I don't have experience with U.K. banks, but I recently got a Visa Virtuon debit card from the Austrian Raiffeisen Bank here in Serbia, so you must be able to get one over there.
EDIT: Visa Virtuon cards are specific in that you can only use them for online transactions, and not ATM withdrawals or regular purchases (they lack the magnetic strip). Our banks offer regular Visa debit cards as well, but I wanted to see how well this one works online.