I had saved thousands using a currency broker, i didnt use XE (didnt get great rate from them), I looked at Moneycorp too, But I used Excel Currencies, I recommend a guy there Ashley Ingle his blog is
Currency Blog | Rates & News Reports | Foreign Exchange Transfers | Ashley Ingle | Excel Currencies (ECFX).
Just using your bank I really wouldn't recomend, you get terrible rates and they dont guide on a good time to fix a rate either.