Why not try one less airport...?
Go:
LHR - MAN BD 582
MAN - EDI BD 383
EDI - FRA BD 3489 (LH codeshare)
FRA - LON BD 3232 (tight on time) or BD 3204
This gets you 50 pts (15 each for the FRA journey) and I think that LH have some good deals on just now so you might want to book with them for the FRA leg instead of bmi.
Wish I could join you but am in the middle of a holiday in South Africa just then (going on LH !)
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Bond Boy