I agree with others that it could be worth looking for a J run - lately there does seem to have been some good domestic specials and D gives full J SC's. I have to say for your plan at the moment looks a pretty brutal run for 110 SC's. My choice would be to turn your BNE-LHR in to a Done 4 - then you can pull some serious credits with an alternate route home. Ticket cost probably less and just think of the joy of planning it all out.