Would you send your relative to Thailand for dementia care?
https://www.carewell-service.com/
It's a lot harder decision than going to Hungary to get your teeth fixed. If the only reason is because its cheaper than a UK care home, then it's because you are putting yourself ahead of your relative.
Difficult to imagine someone with dementia coping with getting on a plane for 14 hours and going to live in a home where English is not spoken .
I would want to arrange a short stay of a few weeks first to see how the relative feels about maybe coming back permanently.