the funds of 400,000 have to be in a Thai bank account in your name only and not in your wifes. When apply for the 90 day non-o vise you can use your uk bank account as proof of funds,also they may ask for a letter of invitation from your wife (family) so it maybe a good reason to get the wife to write a letter inviting you to come and stay then take a photo for your visa requirements
he dunt know what he's on abart if your in Thailand b4 your non-o is approved you have got to leave and reenter to activate the visa to get it stamped in tour passport
you can fly in tomorrow and when your non-o is approved just nip over to nam or loas then come back in on your 90 day visa just print it off to show immigration