you have to get the marriage certificate notarized by the UK government and then both documents translated. You then have to pay the Thai embassy to confirm the translations are accurate
It isn't always about fees. My bank will perform a SWIFT transfer for free, but they only accept transfers in Thai baht, and the exchange rate is unfavourable, so Wise still comes out ahead.
Your money must be in the bank for 60 days, but you can apply for an extension up to 30 days before your non-o expires. You do not need insurance or a police check. Visit the immigration office as soon as possible and ask what documents they require.
If you time it right, you can get nearly 9 months out of a METV, whereas the visa-exempt entry is likely to only get you six months, and that is not guaranteed.
Brandon Thurkettle: Only visa-exempt entries and visa-on-arrival require onward/return flights, so no need to book a cheap flight. I have had trouble with check-in staff at Qatar and Emirates, but when I insisted on speaking with a supervisor, it was quickly resolved. I doubt this is a genuine post.