Nobody would side with the Soviets. They are already widely hated. The UK would see Germany as the far lesser of two evils, and the easier to beat. Remember, France has yet to fall. They still believe the Allies are more powerful than the Axis. Until this point, the Allies have done nothing but cooperate fully with the Nazis, and I see no reason for them not to continue.
Look, man, this is one of the least important parts. Go look at my other posts.