Part of application is prove of current address. If you could prove UK is the address with bills etc. then answer should be the same. Another way is to prove current location with visa entry and hotel booking of current location. That is your Da Nang location.
No. tax is only for money remitted to Thailand. I reckon inter-bank transfer to your Thai Bank account is the only way they could track it. I would have to ask a friend or someone who knows: What if we use foreign ATM card go withdraw money… does that count as remit? No way to track it though. 😂