Does my wife have to take the life in the UK test? the answer is yes but it is way down the line as far as visa applications are concerned as she has to start with the well known UK Settlement visa which is currently 2 years and 9 months after which your wife to get a further 2 years extension will need to pass level B1 English grade in the UK which is fairly difficult but not after your Thai wife has spent nearly 3 years in the UK in which time she will probably be working and be speaking mostly the English language so she will be getting plenty of practice and no time to brood on how difficult the exam is or can be.
At present after your Thai wife has spent a period of 5 years in the UK you then will be applying for a residence permit which comes in two types a limited UK residence permit and an indefinite residence permit at which stage she will have to take the life in the UK test which is knowing all about the UK surroundings and UK history and UK geography so the more she knows the better the residence permit she will get also your Thai wife is given points if she is working and paying some UK tax and UK national insurance so the more settled your Thai wife is in the UK the better chance of a permanent stay and lets face it after 5 years and a long relationship she should be definitely ready.
Most UK husbands/ sponsors worry that their Thai wife or Thai partner will not be able to pass the test but they start worrying at the start of the 5 years not the end of it so try not to worry their are numerous books and also college courses your Thai wife can attend to help her pass the test and as said previously;y after speaking the English language for 5 years constantly she should find it a breeze with your help and a bit of coaching so get her enrolled on a few college classes or private classes and buy some life in the UK test books and start early as learning the English language including slang words will help your Thai wife to settle in to life far more easier and help her with future life and corresponding with other UK citizens and work colleagues.
For more info you can contact firstname.lastname@example.org