Ok, the problem is that the 800K baht has to be seasoned in your account two months before you can apply for your first year extension of stay.
You’ve got a 90 days Non O until 3th of June now and there’s not enough time to apply for an extension of stay on this, you’ll therefore need to be prepared to to leave and re-enter on a visa exemption and apply for a new Non O when you can fulfil the financial requirements.
If you can apply for a new 90 days Non O in country while you’re already on a Non O, I don’t know. Normally it’s from a visa exemption or tourist visa on TM.86 and TM.87.
Not for all countries as Uk. It’s sufficient that the passport just is valid upon your stay. Several other countries demand three or six months after you’ll leave.
I misread your question a bit. Tough they were coming to UK first. But even this would be ok according to UK regulations. But for entering Thailand it’s for sure no problems.
Yes as Brandon says thai citizens will be able to travel and enter Thailand even on an expired passport. And for entries into UK its -unlike some other countries in western Europe- sufficient that the passport just is valid for the duration of your stay.
For several countries you’ll need from three to six months left beyond your stay to enter. However this is not the case for uk. Thailand is no problem.
“To travel to the UK, your passport will need to be valid for the entire duration of your trip.”