Last year I looked at F availability and found nothing for 12 months. Since no MFu is available either it means I rarely fly BA to BKK which is a bit of a stupid strategy as far as I can see for BA, since on my last BA F trip 50% of F was empty. The best way to redeem BA miles seems to be to go with AY or CX to BKK or route via HKG and pick up AY or GF.