I think QF F is entitled but J is not (or maybe it has to be QF Plat+F). I do recall having a treatment when flying QF LHR-BKK. The spa was meant to be for BA to have competitive advantage (and match VS!). The best treatment is the back massage, the others are facial, hand or foot massage; but they only do a limited number of back massages (less than half the treatment slots) so they are hard to get. The Eucalyptus steam shower is also pretty good.