Does anyone know whether it is better to change from pounds to Euros on Zante or will the rates be better if we change the money before we leave the UK?

When I have to buy foreign currency, I usually do it before reaching the foreign destination, usually it is cheaper, saves me time and secures having to deal with unexpected incidents...so i suggest that you buy euros there. If you are still not sure whether it is cheaper, you can always do it in the greek airport. after your stay in greece, if you have euros left, make sure you get rid of all the coins, because they usually cannot be changed back.with notes, there is no problem. enjoy your visit!