However, if the OP (as BAEC Silver) wants to avail himself of the lounge at BKK, then the flight will be announced in the lounge. IME, the lounge staff are very good at timing this announcement, so that you can get to the gate right at the end of the boarding process but without any risk of delaying the flight.

To get to the lounge, follow the signs for transit passengers. The route takes you to the point where four concourses meet - it's a bit like a crossroads. Go up one level. Then head towards the G gates. The BA/QF joint lounges are on either side of the corridor opposite each other, just before the G concourse security checkpoint. First is on the left (with the CX lounge just before that); Business is on the right.

Given that there is a long-ish transit stop here at this time of the year, the lounge is a good idea. (It would be better if the Internet worked reliably, but there are usually too many people streaming audio and video on their laptops and it overwhelms the connection even for the PCs provided.) There are decent showers here - freshening up is always a good use of the time.