What about the Ministry of Foreign Affairs (MFA) office in Chiang Mai. The MFA provides legalization services at the passport office located in Chiang Mai International Exhibition and Convention Centre, 1st Floor, Chiang Mai Province.
The key requirement to gain entry into the UK is you have to convince HM gov that they have a good reason to return home, therefore if thier employed, have money in the bank, own property. Easyvisa in Pattaya is run by a UK solicitor, they can help.
Yes its still a pain. The under consideration period, is needed for the home visit and outside of Bangkok your application is sent to Bangkok for approval. Do you have a Thai bank account?