Like has been said earlier, without well-trained pilots it wouldn't have mattered a lot
The Germans still had plenty of talented pilots in 1942.
But what if Kiev hadn't fallen? With that encirclement, they took out over 700,000 enemies (40+ divisions). By keeping focus towards Moscow, they would have had a massive knife in their flank on which the Soviets would be certain to have even further built upon.
In 1941, the Russian army had plenty of men under arms, but very little in the way of arms. Their soldiers had 1 rifle for 4 men. They had few tanks, few aircraft, and were hopelessly outclassed. But, more importantly, their state was heavily centralized. All C&C came from Moscow, all decisions were made in Moscow, local commanders were scared #%&*$# of Stalin. If the Germans had taken Moscow, then the soviets may well have been made headless. With no orders coming in, the Russian forces would have been extremely uncoordinated, demoralized and effectively neutralized. The germans could have then turned south and rolled up the whole Russian army.
With what would he have invaded Britain with? There were not enough ships for an amphibious assault, no means to provide logistical support, the Royal Navy was ruling the sea and the RAF would've had a field day over England.
They were 5-10 days from wiping out the RAF by destroying the airfields when they switched to London. If they had concentrated on the airfields the RAF would have been out. The RN was an effective force, but the channel is too small for a large fleet to maneuver, and would have been susceptible to air attack. As for their invasion force, Hitler had a large fleet of invasion barges at Calais throughout the battle of britain. They also had airborne forces.
Hitler attacked when the Soviets were still coping with the effects of the purges, and were still unindustrialized. Supported by the great results that the Wehrmacht achieved a year earlier, where they defeated the ghost of 4 years of trench warface in mere weeks, and there wasn't really anything stupid by the decision to invade the Soviet Union.
The issue is less whether to invade Russia, but rather when. Finish of the UK first, then invade Russia in 1942. That would have been the smart play.