Norwegian Airlines has a real deal $160 one way fare from Oakland to London Gatwick LGW on six dates in July from July 9 to July 24 and $185 one way on five more dates between July 6 and August 1.
$160 one way dates: July 9, 10, 11, 17, 23, 24
$185 one way dates: July 6, 13, 16, 25, Aug 1
$210 one way dates: July 4, 7, 14, 18, 20, 21, 31
Norwegian Airlines Oakland OAK – London LGW
You can fly Oakland to London cheap in July, but no cheap return flights on Norwegian until late August
The catch is there are no comparably low ticket prices one way from London to California, so you need an alternate plan or the ability to stay in Europe until late August.
Frequent flyer miles are one option to get back.
Norwegian is $500+ one way for London to Oakland until the third week of August, then drops to $256 August 28.
My strategy I used for my $150 one way Level flight Oakland to Barcelona last week is I purchased a Finnair round trip ticket Stockholm to San Jose to get home to California next week and fly back to Stockholm in December 2017 during the holiday season.
Ticket prices drop to $400s in August for round trip tickets from Europe to California with major alliance airlines with return dates in the fall, like Thanksgiving week.
This is a good fare in July to London with Norwegian, even if you need to pay $45 for a checked bag or $90 for a package with self-select seat, checked bag and meals.