I am doing it from Thailand. I sent my birth certificate to the Legalisation Department in Milton Keynes by post to get the apostille and they forwarded it to an agency who are taking it to the Royal Thai Embassy on my behalf. The agency will then post it back to me here in Thailand. Then I will send it to another agent here who will translate it and take it to the Thai MoFA for their approval/certification stamp. All quite simple really, just a little time consuming, largely due to the backlog at the MK Legalisation Office.