And for numbers sake...
Block times:
CPH-LHR 2:10
LHR-SOF 3:05
SOF-LHR 3:30
Total flying, 8:45
Add 1 hour report prior, 2x45 min turnarounds and (optional) 30min clear = total duty = 11:45.
(30 min clear not required for Flight Duty Period calculations)
From JPM, for a 6am local time start you can do 12:30. So excluding the clear time, you are 1:15 inside max FDP.