The war between russia and germany was inescapable, because of the already differences in the political systems and the fact that hitler saw the eastern people as "subhumans".
But OK, lets play "what if"....
Germany wasn't able to invade Britan, the Germans didn't had the equipment to make an "d-day" style invasion. It was planned to use some "rhine barks" for the invasion wich weren't able to sail over the channel during bad weather making the supply routs a "bit" unsecure.
Also the Britians were able to withdraw their plaes to the north, to scotland, out of range of the germans bombers. The German lacked a big bomber to attack those airfields
(although there were some plans to build one:
http://www.luft46.com/prototyp/me264.html have a look at the penetration depth chart at the bottom of the page, it is quite impressive). So even if the Germans were able to destory most of the aitfields in the south, they would still not have the air superority to succssesful invade england
But on the other hand the german army would not suffer they way it did in russia, so they would have been able to defend themself against the allied invasion. D-Day would surely have been a defeat for the allied.
So this war would have been a stalemate. Germany not able to deliver the final blow to completly invade europe.