I have a Nationwide Flexplus account which allows free cash withdrawals (up to 500 euros a day)at the commercial interbank rate and then deposit in my french bank account. I have always obtained the best rates of exchange at no cost..
I realise that the last post here was about 2 years ago but I think my latest foray into changing cash may be of interest. I have, until recently been using Norwich and Peterborough Building Society as my main current account as they give commission free withdrawals from ATMs.
However, the parent company, Yorkshire Bank, has decreed that they are reverting to being solely a building society and all bank accounts are being closed.
Looking round for a replacement I found that Metro Bank is offering commission free withdrawals,
7 days a week counter service at their branches and internet banking services.
The downside is that they only have branches in the London area at present although they have an expansion program. You can only apply for an account in branch and they carry out quite comprehensive residential checks.
I have had my account now since March and all is well. I've not had any problems with the Mastercard as yet and the rate of exchange is equivalent to the Euro rate on the red button on Sky.
May be worth checking out if you live in or have access to an address in the Greater London Area.