It really doesn't matter, but likely the receiving bank if you send Sterling we'll have a worse foreign exchange rate than the app you're using. Check the rates and fees first.
Remote worker is generally understood and accepted as a digital nomad, working online from a remote location. Not necessarily working some labor or desk job etc in country x.
show your debit transaction from your foreign bank date and amount, show the same going into your Thai account with whatever Thai paperwork you can, any reasonable officer will accept this one off paper trail as evidence.