What if the Germans did a Battle of Britain lite, a feint to get the British and Soviets to think the invasion of Britain was a real possibility, but in reality the Germans never are going to really invade and try to hold down aircraft losses, especially in bombers.
In practice this means fighter sweeps along with a minimal number of bombers (Ju88s), while preserving the HE111 force for the Soviet Union.
Gather half the barge force as in OTL to avoid disrupting the economy so much.
Hopefully the minimal bomber force won't hit civilian targets in London and not provoke a British reaction.
But regardless of the particular lite strategy, hopefully several hundred bombers could be saved.
Could say 400 extra bombers over the Soviet Union make a difference???
Perhaps at Leningrad OR the siege of Odessa or closing the Smolensk pocket earlier???