@ The rest:
If Hitler had not invaded Russia or had fortified his postions and territory in it till winter stopped limiting his advance further in Russia, we may have had another situation altogether. It was a known fact that against the Brits, the Germans had an inferior Navy - UK had the territorial advantage on an island - they used it pretty well. Invasion was almost impossible, even a blockage was not possible.
I've read from sources that the reason why he let off those English soldiers and was very soft towards the Brits is because of his adoration for their colonial successes. Historical sources have suggested that Adolf never wanted War with the Brits in the first place - it was after the Polish invasion where it hit him in the face. His letting off of the English troops was a sign of truce - the only thing which baffles some is the bombing of London. Most likely, the latter to show them the German might, which makes no sense but is typical of the man - aggression.
In all, I think they might have become allies if the conflict had not involved an automated initiation of the treaty between the allies and Poland. I think the Polish were hated for occupying German 'territory' anyways - invasion was inevitable. UK entering the war is remnicent of Germany under Kaiser Wilheim and the Balkan Conflict - which ironically is called World War 1. It was completely stupid.
It's funny though. Two European conflicts labeled World Wars. I don't remember my people being in the War, and we've nearly got 1/6th of the world's population.
It all comes to resources and manufacturing capabilities.
Main defeat Hitler got in 1942, when he failed to capture Caucasian oil remaind limited tank forces. Russia alone manufactured much more tanks than the whole Europe under Hitler. But in addition to Russia, if you remember, Hitler was fighting two strongest economies of the world – American(*) and British. He had no chances. It is surprising that he did as much as he did.
(*) America, of course, was tied in war with Japan, but its economy was strong enough to supply Brits and Russians with a lot of helpful stuff.
The only thing about it is that Russia would not have been out of it. Russia controlled the oil that Hitler so desperately needed. Stalin already was making demands on Hitler. Hitler knew it was only a matter of time before the fate of Germany rested solely in the hands of Stalin. the non aggression pact lasted about as long as Hitler could let it last. As it was Hitler still ran out of fuel.
The battle for Britian was very close. There is evidence that Hitler never had real intentions of an England invasion. If he really planned it I am sure it would have been successful. As it was they did not have adequate landing crafts for a marine invasion. Feslin is correct however. If hitler did not make a stupid decission to bomb London instead of putting the death blow to the airfields and planes on the ground, they would have had cmplete control of the airspace over Southern England.