There is a lot of information on the Web try a search

as far as I know you can only apply at a certain time of year

Check Web

Edit do

Wy

You need to prove that you can support her when she visits the uk you do not need an agent to do this just write on form that you are happy to support here and give evidence by meats of a bank statements etc a return ticket a place to stay in England

They only refuse visa if they thing your partner will not return to Thailand she does not have to have a job just your support

And proof of relationship etc

@Peter *********

yea you will need yo show 0 bht for 2 people being in the bank for 2 or 3 months don't see any advantages in using an agency

It's OK to do your self but a lot of paperwork may have to go to immigration more than 1 time but not realy a problem I have been doing a marriage visa for 4 years now

Just confirm that you can support her best way

Should be in the account for 3 months but depends on immigration office

Leter or statement from bank on the same day copy's of passport pages 3 months bank statements

No problem