Just go onto Expedia and try it. Not sure of when it runs until, but I tried it last week (for a week in September) and it was showing about £1600 for F class LHR-BKK, with the DXB-BKK sectors on the A380.

I assume this would allow the free stopover in DXB.

There's also a 2-4-1 offer at the moment which works out at about £800 per person in J class.

Cheers,
Rick