I had 2 Paypal accounts, one Euro and one Sterling. You can unlink your Paypal account from eBay and link another (or you used to be able to), but as already stated, delivery verification may be a problem. You have a UK bank account, do you have a UK credit card?
Alternatively, you can elect not to accept the Paypal conversion on purchases and rely on the bank rate (okay in reverse for Halifax Clarity and Nationwide (still free in EU I think) credit card holders). When I purchased from China in USD, I took the latter option and saved money on each transaction, it is similar to refusing the dynamic currency conversion at the ATM. That said, Spanish banks charge for card use don't they? Paypal may be the cheaper option.
Mark