I don't see your problem. You are spending less than your balance. I assume you are buying on line so you just quote your debit card number as usual when buying online. The price being in $ makes no difference. It's just like using your card abroad.
Your bank may cover it if you have an overdraft arrangement. But if not the payment would decline instantly. Be aware that if it did go through and you did not have banks permission or went over your overdraft you could be liable to a fixed penalty. consult your bank if you need a borrowing option.
Yes just pay it from your bank account, your bank will convert it into dollars and pay them...duh.
I want to register for Google Developer and it is telling me to pay a fee of $25. I only have ￡20 in my bank account will it still let me pay the fee? $25 in GBP is roughly around ￡15
