From OP
Question from a novice - we are flying into BKK from USM at 1520, with an onward connecting flight on TG at 0030 the next morning (business class)
From Richard1148
The OP did not mention if his/her flight was domestic or international. I assume domestic, as why else fly into BKK, but I want to make sure that I can be flying domestically in biz on TG and have access to the lounge.
Richard. USM-BKK is a domestic flight (Koh Samui to Bangkok, Bangkok Airways only as USM is a private airfield). There are no TG domestic flights departing at 0030, but plenty of international flights. So it wasn't too hard to work out the onwards flight (in TG C) was international... "Elementary, my dear Watson"
Cheers, TK