Your wife does not need money in her account (my wife had none)
You have to prove that you can support her financially
When I went through this my wages had to be over £18,500 this is going to rise to £29,000 in spring this year
In addition to my wage you will have pay a NHS surcharge which in my case was £1200 for the first visa application
You will also have to present plan of your living arrangements plan of house ownership or rented if rented rental agreement
It is a lot of paperwork including photos over the past years of you and you wife together proof dates travelling to Thailand over the past 2 years a the hotels you stayed at
It’s a long journey I went for the 5 years route
Which has now ended and my wife is a British citizen
I wish you well on your journey
Not sure if you will see the £5 k again but I hope so
do not forget to have the Thai Marriage certificate translated into English and stamp by a solicitor it will help if you decide later in life to move from Thailand