The only credit card I'm aware of and is widely available, that may allow you to pre-load and potentially get free ATM withdrawals (not including the local ATM withdrawal charges in Thailand, which are avoidable) is the Abbey Zero MasterCard credit card.

Of course there is the small chance that you could get an exchange booth to use your credit card and put the transaction through as a 'purchase' not a cash advance, there by getting your interest free period and not having to pay any other charges associated with a cash advance/withdrawal. This has been / can be done, but I haven't seen it mentioned much. Of course you would be at the mercy of the booth's own exchange rates, potentially.

Regardless, credit card wise, I think even with the .84% Visa charge Nationwide are passing on, and given the good exchange rates provided by Visa compared to Mastercard loading the exchange rate by 2-3% (as I have seen mentioned on TV), the Nationwide credit card would be the most cost effective.

What would be very useful is to have a good comparison of Visa's and Mastercard's exchange rates for GBPTHB, EURTHB and USDTHB. I haven't seen a good and thorough comparison of these yet...

Nationwide have refused to issue me with a mastercard or cashcard as I already have an account which has a visa card, they say it cannot be changed or downgraded and I would need to open a new account to obtain a new card. Not possible if you live here!