DutchSE.

I am trying to understand what you want to achieve, I guess you want 20k status miles to get to SE.

Many ways you can do it, Not sure what your timetable is like and weather you can take time of to fly but here are some suggestion.

On UA
LHR-LAX via a few places like IAD/ORD.

Leave LHR on a Friday, arrive LAX on a Fri night, SAT am take a AC Flight, LAX-LHR via YVR.

So to put simple.

UNITED.

LHR-IAD-LAX Nov 7th

LAX-IAD-LHR Nov 16th.

Cost approx 500euro

Air Canada.

LAX-YVR-LHR Nov 8th

LHR-YVR-LAX Nov 15th.

Great L fare for 600 cdn or 250 euro

Total miles will be about 21k

And you are only away weekends, it called nesting but with two different airlines I don't think it matters.

so for about 750 euro and a couple of night hotels your done, if you have to go from Holland then take a cheap BMI flight and have more Q miles and do the UA direct to LAX.

Have fun and welcome to this addictive world.