You can get euro currency in the UK at the Post Office, in many travel agents (including Thomas Cook), or at the airport. 

In this area of Spain, banks DO NOT ACCEPT TRAVELLERS CHEQUES due to forgeries and therefore it is best to bring euros in cash for initial purchases and payments.

UK bank and credit cards can be used in cash machines to obtain currency but are not always working or may be empty at busy times! 

Try the UK Post Office website for HOLIDAY money exchange rate (as opposed to the higher Business exchange rate) http://www.postoffice.co.uk. At the very top, there is a tab for "Currency Converter". Select a currency and how much you wish to exchange.

Alternatively, click on Travel then Foreign Currency then Exchange Rates then Foreign Currency Notes then Select a currency and how much you wish to exchange.

If the link above takes you to a Royal Mail website, click on Post Office Customer Services

Or try the Money Saving Expert at this link - http://travelmoney.moneysavingexpert.com/

Current BUSINESS rates are given below - High Street rates may be up to 5% lower. Use the "Back" arrow after viewing the XE.COM conversion.