There’s no information indicating anything will change with the 30 days tourist extension. If the exemption goes back to 30 days you’ll have 30 days upon entry and still can apply for a 30 days extension. You can also apply for a 60 days tourist visa online through the Thai embassy in London before you leave.
It’s known that some smaller immigrations don’t do Non O in country but normally they offers to send your application to a bigger district immigration. I’ve seen similar feedback previously from the area you currently stays.
Requirement can vary between immigrations. Best to visit your specific immigration and get handed over their list for applying for a one year extension of stay based on your Non O visa based on retirement.
If you don’t get a affidavit letter from your embassy, you’ll need to prove 800K baht in your account two months prior to your application.
Ok, good the requirements varies but this is normally the general requirements I guess. Some accept a affidavit letter and some don’t too, and it’s of course always recommended to get handed over the specific requirement at your immigration first.
You can apply directly for a 90 days Non O based on marriage and the financial requirements are 400K baht in a Thai bank at date when you apply.
Within 90 days you can apply for your first year extension of stay (as several people names one year visa) and the funds needs to be seasoned for two months prior to your application.