It's very easy and quick to get the Thai passport as I remember and just costs 1000 bht. Unless she entered into the country on her British passport I imagine she will have some issue as she won't have an entry stamp.
I never understand why admin remove some comments here. I advised to just leave an ATM with his Mrs and comment gets removed. Its a simple solution for him as his concern is giving his wife access to the cash if he dies. Only difference is her name won't be on the account. Very simple solution to his problem.
it's going to take a while. I speak to my customer there regular on chat and he's been stressing the last few weeks even though he's double vaxed already