SS255, you should definitely enjoy the NCW (New Club World) between LAX and LHR.
I am not sure of the load from LAX, but from SFO, I have been on several flights where there appear to be a decent chance to be operationally upgraded to BA F when they rolled the cabins forward due to oversell.
BA has three flights a day from LAX, operated by two different versions of their 747-400. Two of the flights are operated by the version with 38 NCW seats, and the other by the 70 NCW seat version. Of course, there are always possibility of equipment substitution.
If you have not already done so, you might want to check out the SeatExpert BA 747 seatmaps:
38 NCW seat version
70 NCW seat version
Rows 12-14 on the main deck, and the entire upper deck is the same for both versions, it probably is better to select seats in these rows to avoid problems due to equipment substitution.
As for miles, you could credit them to HP and get 25% class of service bonus, and the base miles are actually counted toward status on HP. On the other hand, you might seriously consider joining BA's Executive Club program, where this one trip would earn you about 18,000 BA miles:
- LAX - LHR - 5450 miles x 2, plus 50% class of service bonus = 16,350 miles.
- LHR - HAM - 450 miles x 2, plus 50% class of service bonus = 1,350 miles.
Keep in mind that BA miles is probably one of the most valuable of all FF programs, since you only need 25,000 miles to get confirmed round trip upgrades to the NCW business class between US and Europe.