Come on a 60 day visa then apply for a retirement visa or get a multiple entry 60 tourist visa can stay for 6 months every 60 days you need to do a visa run to get another 60 days,or chance it on multiple 60 day exemptions doing boarder runs
tried Elton get bank account in Ban phe Bangkok bank filled in all the paperwork the bank workers were very helpful right at the end computer said no had to have 60 days left on my visa,as I had a 60 day multiple entry tourist visa I would of had to do a visa run and open the bank account on the same day.
I am doing the same ,came on a 60 day multiple entry that last 6 months so every 60 days you have to leave and returned and get 60 days each time, this can be done right upto the last day of your multiple entry visa that lasts 6 monthes then you will get another 60 days so you can get at least 6 months easily, even more, it costs £150 on line from Thai embassy in London.
This may look like the best option but buy the time you have paid £150 plus a boarder run every 60 day costing more money and being a pain ,I decided to get a 1 year retirement visa which was sorted by an agent quickly and simply,you don't need to have the 800,000bht in the bank the agent sorted that for me,in the long term it cost less and a lot less hassle .
If you want to know anymore detail Message me.
My retirement visa has to be renewed each year but the agent sorts it all out for
bht(£370) they will sort you a visa for a year without the need for all the checks or money in the bank, they will even sort you a bank account out that is required for the visa for additional cost,you will also need a Thai drivers licence after 6 months,don't forget the international drivers permit from UK to allow you to drive in the first 6 months on your uk licence.
You might get 60 days as it is changing from 30 to 60 soon.