If I were in direct transit then I think I would have access as arriving in DOH from LHR on A380 in F and onward in J as that is the highest cabin available on second sector. Fare basis is A/J
However, if arriving in F on A380 from LHR but having a 4 day stopover in DOH, before onward connect in J (9 hr sector), can I checkin at F and use F lounge.?
On my return, I have straight transit at DOH so can use F lounge as sector on A380 in F
i should add, for completeness, that A380 F flights are under BA codeshare, should that make a difference.