I've used the USAA credit and ATN/debit cards all over Europe and Asia with no problems. There are always network fees of 1% charged, but I've never seen any other fees for ATM use and such.

Regarding opening accounts in UK, don't know, but I'm sure your daughter won't be the first, so she should be able to get plenty of advice.

One other suggestion: Get a skype account if you don't have one. Make sure she gets a UK cell phone too.