it’s odd really , if you ask why they don’t take your notes with marks on them they say it’s because they can’t give them to other people who need a non Thai currency
So surely that applies to the notes they give back to you in exchange
Makes no sense to me so I just make them take any marked notes back
I’ve often been given Thai notes with marks on them ,when give them back for exchange they get upset, but are quite happy to pick out any marked notes in your currency
If it’s a 6 month visitor visa , my wife and I have done this several times over the last 10 years, you only have to prove you can support her whilst she’s in UK
If it’s long stay there is an earnings level you must achieve before they will grant it