Does your Immigration Office accept the monthly international transfers for an Extension of Stay based on marriage as many don't which could explain your bank's response?
All Visas are now online and all UK Consulates are closed. You can get the Non-O marriage visa which gives you 90 days on entry then the visit Thai Family 60 day extension to give you up to 5 months each stay or go for the full 12 month extension of stay each year (no visa then needed for subsequent year if the extension is still valid and a re-entry permit purchased).
Next year you should start your planning much earlier as in Bangkok you can apply for your extension when you have 45 days or less remaining on your current stamp