@Cissi ********
Yes it's difficult...but keep in mind also, that unless the applicant is heading for Nigeria or somewhere like that to apply (the OP states that this is not desirable) then even getting a visa for Laos, Cambodia etc is as complicated as Thailand.
Don't assume nationals of countries such as Ghana can easily, or more easily enter Thailand than neighboring countries. It may actually be the other way round.
Also, Laos imposed a prohibition on nationals of several African countries entering in mid 2022 as a precaution against monkeypox. I have not seen any official notice stating that this ban has been lifted. Maybe it has been, maybe not (then there's the second WHO warning from August 2024, which may have influenced some governments to impose new restrictions).
Anyway, it's going to be tough. I can't really offer any more suggestions. The OP should try their best to convince the Thai embassy in the UK, since that's where he applied and where his wife is located.
Applying anywhere else sounds like it is fraught with difficulties.