ATM'S

No British bank will charge you a fee for using their ATMs.

All the fees (if any) will come from your bank; some US banks have an agreement with some foreign banks which means your bank will charge you less if you use a certain ATM but you'll need to ask your bank what they charge.

There are some private ATMs in the UK that charge a transaction fee, usually in convenience stores and such places. They're a minority and most tourists will rarely encounter one - I only mention them because I'm sure someone else will and I want to make sure you have the full details. By law these ATMs must notify you of any charge, there will be a sign on the ATM and you will be notified on screen if you process a withdrawal so you will not be charged without your knowledge.

European bank ATM's do not charge fees. All fees will be charged by your US card issuer. You can compare fees here: http://flyerguide.com/wiki/index.php/Credit/Debit/ATM_Cards_and_Foreign_Exchange . Barclays is a good deal for Bank America debit/atm card users. "No fees for ATM withdrawal at the following banks in the following countries only: Barclays (UK), BNP Paribas (France), China Construction Bank (China), Deutsche Bank (Germany), Santander Serfin (Mexico), Scotiabank (Canada and Peru), Westpac (Australia and NZ). [9] All fees may be waived for Premier Banking and Private Clients with a call to customer service."

Check with your local banks and credit unions, too. My small local credit union charges me nothing when I make a withdrawal overseas - I've done so in China, Costa Rica, and all over Europe without a fee.