So, it seems increasingly likely that despite the "confidence" and bluster of ChalkyDee, that what he is doing is paying a lawyer to sell him a thing that he cannot buy - namely, dual Thai-British citizenship. What ChalkyDee seems to be at
risk of doing is either:
a. losing money to a lawyer who either has his facts wrong or may not be being honest; or
b. giving up his British citizenship to get Thai citizenship, without the supporting documentation required to be able to resume his British citizenship.
The former seems to be the more likely outcome... you pay someone money to give you the answer you want; then years down the line, something may happen that completely pulls the rug from under you, and you have no recourse for action - you're fucked. That would wipe the smug grin off anyone's face.
That's not the kind of "experience" anyone needs...
...if you are at risk of doing a very stupid thing, being abusive to people who are trying to protect you from yourself seems rather silly.
I think this map is not up-to-date, because I don't think Cambodia allows dual nationality.