You will always receive a better exchange rate in your destination country.
Today vicinity €1.19 to £1.

I see from your other post that you're staying in (or near) to Montemar/Torremolinos.
You will get a better rate in the resort, although there will be slight variations between the exchange places.

Rubens in Benalmádena give the best rate. The rate you see advertised, is the rate you get - no hidden charges or other naughty 'conditions'.

From Montemar, walk on the promenade towards the Puerto Marina, walk along the back of the Puerto and you will see some steps ( there is an old tower nearby) - Go up the steps and halfway up the street on the left hand side is Rubens shop.
The other way is -- walk by the side of the main coastal road into Benalmádena and turn left down Ave Alay - the office is on the right, tucked between other shops.

This map will show what I've tried to explain.

http://www.rubenexchange.com/office.php

http://www.rubenexchange.com/

Sanji