Thanks guys for the help. I guess I will try to KUL option- whenever I have flown LH from SIN, the flight was full, have never flown TG recently, so was checking what the load factor is like.
I know that we need 2 vouchers for the BKK-LHR sector with TG, but we are sitting on 12 vouchers (4 each from LH and my 4 SK *G ones) which we have not used since we have not gone longhaul much yet- and time is running out to get rid of them!