I'm looking at one-way award flights from LHR-SFO for the period of around April 21-27th. Is there any way for me to search for ones that have E+ available?

Also, I was thinking of leaving from any number of other European cities but it doesn't appear that United offers seats on anything ex-Europe to SFO in the April/May period. Does that sound right?

I'd also add that I'd (grumpily) consider a saver biz award but there don't seem to be any available during this period from LHR.