If you arrive tomorrow in Bangkok you can stay up to 9 months with some visa runs and extensions

Education Visa.

First step is to get married in Thailand. Your long term visa is not a priority right now. You can apply for a METV Tourist visa that will give you around 6-9 monthsto stay legally in Thailand. Ask the Thai embassy what documents you need (for marriage) from UK governement and collect these documents while you are still in the UK. In the meantime your lady can also collect her documents in Thailand. When you have all the documents you can now travel to Thailand and get an appointment at the Amphur office. Let your lady handle the paperwork in Thailand if you don't speak Thai. Once you have the marriage certificate you can talk with an agent to see wich visa is best in your situation (marriage or retirement). You can also use a agent to get everything in order to be able to get married in Thailand. I've figured out that Thailand is an "Agent" culture and everything will just go more smoother with the right agent. You can do all of this yourself but up to you if you want to save some money and try to complete it yourself. Some people losing their minds if they think about paying an Agent £1000 to get everything fixed and other people are very happy to pay the money and go on with their day and don't have to think about it anymore 😀

@Tod ********

My post above does not matter anymore. I've just read from another post by you that the 400K can be in savings account in your home country/bank. Didn't knew that and that make things much easier to apply for a marriage visa one day. 👌

@Tod ********

So if i understand you correctly: First year put 400K in my thai bank account and apply for Marriage visa. When i have my approval i need to transfer 40K every month from my home country directly to my thai bank checking account during my first year. After doing this for 12 months i can apply for extension the marriage visa and use the proof of the 12x "40K deposits" and i can transfer the 400K from the first year back to my home country bank account and keep continuing the monthly 40k deposits to my Thai bank account. Even if the account goes to 100k because i use the money to live and pay expenses in thailand is fine as long i keep depositing 40K every month into the account...

@Tod ********

40K monthly income is also allowed i've read. How do we proof to Thai immigration your income if you're self employed? Provide tax returns from your home country?