Bank card

England is one of the few European countries where we've never had a problem with ATM's. There seems to be a bank or two on every street in central London, and they all seem to take all cards. One tip: if you use your BofA card at Barclays, BofA won't charge you the fee they ordinarily levy for using an outside bank's ATM. The two banks are part of an international partnership, along with Deutsche Bank, BNP Paribus and some others. While I wouldn't go very far out of my way to save on that fee, Barclays are very easy to find in London.

The card issuer is not important for using a ATM but the network is critical. You need to look for an ATM that takes the PLUS network (VISA). Generally the ATM will indicated that it accepts Plus, Cirrus, and couple of European networks. But for a VISA card you have to have PLUS.

If you go to Barclay's website, it will show you the nearest Barclay's ATM to your hotel.

B of A is one of my ATM's and for every trip to London, I have my list of nearby Barclay's. You'll also find their ATM's all over Heathrow.

Barclay's. That's what I use whenever I go to London. They don't charge a fee for using the ATM and they're pretty prevalent through London. It's the most convenient thing to do by far. Credit card companies will assess a 2%-3% transaction fee usage. I would not recommend traveler's checks. They are too inconvenient.