Originally Posted by
Expatbear
If you're flexible on dates (within a few days) and flights (the 777 service seems to have more award seats) then I've usually found availability in J and WT+ quite easily 6 months out.
However I'm struggling to find two J seats back home from SEA to LHR in June at the moment...

I don't think this will help the OP - sounds like they're pretty short of miles.