That's odd. I'd heard it's in New York with Donald Trump of all people. They've gone off to meet that group of Russsian women he knows. Hope its got a decent cover. More than Trump has!
Thailand is never particularly low-priced for dental treatment, though it is cheap as against UK. I have had work done in Turkey, Malta and Thailand with Thailand by far the most expensive. Prices are also very similar practice to practice in Thailand, perhaps practices specialising in expats and dental tourists a bit more expensive, but only a little. It tends to not be worth the effort shopping around too much.
Blended learning is OK for an Ed Visa. I've no idea what the rules are on that or if there are formal rules, but that only alleviates you some classroom attendance, not all.
That is true. It isn't an Embassy service. It is outsourced by the embassy. Got one maybe 3 weeks ago. The only question is whether VFS will play ball if you haven't completed the whole process here. You can but ask - and they seem quite a decent, helpful bunch. It's all in the words. It could also be that if you popped into the British Embassy they would say a simple "No" - they are not very helpful people - rather than advise asking VFS Global. I note that the letter is very new, so I suppose another question is whether they've now stopped supplying the letters to VFS Global. All this said you never did need that letter anyway. So the final question becomes whether the individual immigration officer is fully appraised.