First 90 days report after re-entering Thailand you’ll need to do in person. After you can do it electronically. Ask your immigration regarding update of your TM.30 each time you re-enter. Some demand update, some don’t require it as long as it to the same address.
Yes you just show both passport in the immigration and you’ll get stamped in on the new one. You can visit your local immigration and get your stamps transferred to your new passport.
Do you have an official statement or general list regarding fees at the immigrations? Sometimes I’ve paid 300 baht to register a TM.30 and 500 baht for a residence certificate, sometimes I’ve got it for free? So if you have an overview I’ll be grateful.
Marriage it’s another question and you’ll of course need to prepare the required documents before you go. But on a 90 days stay you should have time both to get married and apply for a 90 days in country. Took me one day to order the documentation I needed before leaving and two days in Bangkok, one at the embassy and one at the Amphur. And if it’s an issue you can easily get an agent to assist you with the process before you come and through the marriage registration.
If you come on a 60 days visa exemption or a 60 days tourist visa which both can be extended with additional 30 days is not important. You can apply for a Non O in country with both.
You’re problem is a bank account for banking the required 400K baht for Non O/extension.
As I see it you have two options;
-Just come and get married and contact an visa agent as
who are able to assist you with opening a bank account included in assistance with the whole visa process.
- Come and get married and get all your papers, leave Thailand and apply for a Non O through an embassy in a nearby country with your bank at home to meet the financial requirements. Not a duckwalk but still possible to open a bank account in Thailand on a Non O visa and a residence certificate even though you might have to try in several branches first. Bank the 400K baht two months prior to your application for extension of stay.
You don’t need six months left to leave Thailand and you’ll anyway be allow to enter UK with a valid passport. But always good to renew a old passport and it’s free to transfer your stamps at the immigration.