1. PER-NRT-LHR is a possible route, but there's no availability on NRT-LHR on 2/12 according to expertflyer. If you could stay one day in Tokyo:
QF79 dep 1/12 22:10, arr 21/12 08:45
BA6 dep 3/12 11:00, arr 3/12 14:30
(can't depart PER on 2/12 since it's not daily).

2. No.

But you have a load of spare segments, so how about:

PER-HKG-BKK-HEL-LHR
30/11: CX170 dep 12:50, arr HKG 20:35
30/11: CX709 dep 22:00 arr BKK 23:50
1/12: AY96 dep 12:35
1/12: AY835 arr LHR 20:40

all have D according to EF.