I know we're funny foreigners, but we both get our pensions paid in Sterling. We have a Nationwide account - and if we use a cash machine over here to draw euros on it, we get the BANK rate applicable on that day and time. Not the tourist rate, not some funny number, but the rate quoted on the Foreign Exchange sites - and no charges, natch. Anyone with a Nationwide account might consider this as their cheapest option.
When we lived in Kent, Termie found the Post Office was the best way to get a dollop of euros at a good rate. That may or may not be true today. She generally had to give a day or two's notice - but the PO was very obliging.