If you’re already in Asia and decide to apply in London and get denied, that’s on you. You should apply in the same country where you’re currently staying. Most embassies outside Southeast Asia only accept applications from citizens or residents of that country or nearby ones.
Depends where you apply for example in Helsinki they accept only Finnish or Estonian bank statements. If you have any other EU or even non EU bank statement they don’t accept. It says on their website. So better to check requirements where you apply
on Jakarta Thai embassy website it’s states clearly for some African countries can take 4-6 weeks to process visa. Other countries has different list for countries which take extra time to process. So best is to check Embasy websites in countries around Thailand. And UK probably has same requirements as EU only citizens and residents can apply. Tourist visa don’t count as resident.
where you read that most countries from Africa are not eligible for DTV ? Embassy in Nairobi issue DTV visas and I am pretty sure other embassies on continent do same.