Maybe a weird question, but what I understand is that you're still in the UK... why go through all the hassle and just for apply a non O to begin with... then all you have to do is to get your yearly extension instead of turning visa into an other one and some IO are not willing to do that... than you're screwed
You need to have 400.000 baht on a bank account in your name only, I personally have a savings account, be sure that your 400.000 baht has been in the bank for at least 2 month prior your application. Make a copy of your bank book of the last two months prior your apply... after you've applied and you get a 30 day under consideration stamp, leave the money on the bank and when you return to your immigration to get you yearly extension make sure you have a new copy of the last month from your bank book.
Be sure to keep the money on the bank until your 30 days under consideration is finished, cause they might ask you a new updated book bank when your 30 days are done and you come fo pick up your exrension
Im no pro in this... but you already have an extention of stay for marriage... why change that one for study and then 3 years later when you finished your bachelor..change again for marriage... seems like a lot of work for nothing... unless you can't study with the extention of stay for marriage.... that i dont know
Yes they explained at the Immigration. . I am not planning to leave anyway so that is no issue and I've set the alarm already for my 90 days report... but thanks for bring it to my attention