I have been doing so much research into this and the post office on line is good (but you get charged by your bank for using a debit card!), if you go into the post office branch you only get 1.03!! (as of Saturday. The best deal I found was in Thomas Cook/Airtours Branch, if you go onto their website you can print a voucher of giving you 1% cashback. With this I had 540 euros for £501.93. £5 cheaper than M&S, and Thomson and certainly the post office. 7 days until I am in Salou