you should be ok when she go to British embassy in Bangkok they should let her know all what she needs from you to send to her via email best of luck and enjoy your time together
You need to write letter saying your going to sponsor her and give your address plus last 6 Months payslip plus proof of your address this is what I had to provide when my partner came in April but she is government hospital worker and has a 10 year old son don't know if this makes sense
Correct me if I'm wrong I'm planning on getting married to my thai partner next year and living with her from December next year I'll be 60 do i have to have monthly income or live of private pension