Single Entry Visa from the UK.
Providing you aren't unlucky enough to live in London, or even worse, Hull (I know, I know, it's a joke, imlobe London really....), the only way to apply for a visa is via post, to the embassy in London. I just this second posted an application, and this was the cost:
£25 for the visa + £10 return fee. They no longer allow you to include a self addressed envelope (even special delivery). So £35 total, payable only by postal order, in the post office. This incurs a fee of £4.38. So for the visa 25 + 10 + 4.38 = £39.38.
The application must be sent via royal mail special delivery, this is £6.45. They usually provide a special envelope, but today I had to provide my own (the guys in this particular office are dicks)
So the total price is £45.83. At todays measly exchange rate that's around 1900 baht.
I already had some visa size photos lying around, but I checked the machine at the nearby Morrisons, and Visa size photos were £7. In the past I've gotten away with passport size photos, but it's probably not worth the risk.
If you are staying for more than 30 but less than 60 days, and you don't have time to apply for a visa, don't sweat too much, money wise there's not alot in it. I'll always apply if I have time though, providing I need more than 30 days of course.
TLDR : Answer Summary
The process of applying for a Single Entry Visa to Thailand from the UK primarily requires submitting the application by post to the embassy in London, except for residents in close proximity to other Thai consulates. The total cost for the visa application is approximately £45.83, which includes various fees related to postal services and visa processing. There are alternative options for those staying more than 30 days, such as entering Thailand with a 30-day visa exempt stamp and then extending that visa for an additional 30 days at an immigration office in Thailand for 1900 baht.
