Liking the new name for the immigration office by the way ;)

You can also extend those 30 visa exempt entry stamps at immigration offices inside Thailand if you need to.

Thai embassies and consulates usually only allow nationals of the country they're in, or people with residential status there, to apply for the METV so you'd need to check their requirements for that and make sure you have the evidence they require, but yes, that's the visa that will give you the longest time in Thailand (with a options to extend that once you're there).

Also, getting the Tourist visa in London keeps your interaction with the embassy to a minimum. They're not big on helpful advice, and to be honest, they're a bit odd lol

Best to do all that stuff when you're in country. You're going to have to be actually present at certain government offices to get all your paperwork sorted out, work permit etc. Plus you minimise the risk of being overcharged, given the wrong advice, picking the wrong law firms etc etc.

You can get some of it done before you arrive, but boots on the ground will give you a chance to make sure everything will be done in the best way.

Sounds like an interesting project by the way! Good luck with it all.

Or do the visa by post.

That could end up more expensive than getting a visa. Certainly more expensive than buying a ticket to, say KL with Air Asia or another similar airline.

If I was faced with a more than £40 expense of getting a visa from the Thai embassy in London I'd buy a throw away ticket. Currently it only costs me the visa fee of £25 so I usually go with that option.

Cheap flight out is certainly another option.

I've had at least four Tourist Visas from London. The check in staff at LHR have checked for a visa in my passport every time.

The Thai embassy in London will accept applications by post.

-How-to-apply-visa-by-post.html

If you want to risk being refused boarding at the airport, then that's your decision. Personally, I wouldn't risk it.

Yes, it's entirely possible that you could be going elsewhere. However, the airline will look for either a visa, or a ticket out of Thailand within 30 days because if you are refused entry at the Thai border they are responsible for flying you home. If you have a visa, they aren't. So that's why it's a problem.