The beauty of Travelex, changing money or buying euros is extremely convenient at the airport. Travelex provide a great service for travellers and you will always find a Travelex kiosk at every UK airport.
For anyone who is watching the pennies the Travelex retail kiosks are probably the MOST expensive way to change money.
Buying currency from the bank or post office ahead of time you are going to get a significantly better rate and my advice, NEVER insure or guarantee a buy back rate from Travelex. This is a great way for them to make extra money.
If I’ve got money left over, I’ll take it to the bank or even better, stash it in a drawer for the next trip, like a secret vacation savings account you’ll definitely forget about.