Hi, i'm currently on Thai non-B Visa, and i'm going to apply UK trouist visa in BKK. Does anyone have idea whether is possible to do that in Thailand? If so, what docs they required? and how much funding do I need in bank acc. Many thanks !

If you're legally resident in Thailand you can apply for a UK Tourist Visa in Bangkok.

You don't need a level of funds in the bank but you need to satisfy the UKVI that your proposed trip is affordable and genuine and that you are likely to leave the UK on the conclusion of your trip.

All the details and requirements can be found here http://www.vfsglobal.co.uk/thailand/ and there is a pinned topic that will answer many of questions at the top of this forum.