A really simple one is use the MSCI world index fund inside the Wise account. You could do a lot worse although there will likely be a correction soon. Your age and investment horizon matter. If you're UK resident you should be doing tax returns and reporting any capital gains and dividends. In Thailand dividends are treated as regular income. Go see an accountant
I know people that do it. They either get a little bit of help here and there and so they don't really do it or they're as miserable as hell. Realistically 60k will do it....just....if you have accommodation ie bought a condo then on 60k you'd be in clover and 40k you'd be ok
I have a very simple rule. Ask yourself, really seriously, if she was in the position to do so, would she do the same for you. Really ask yourself and maybe even ask her. That's the acid test