[44 AMP]

Operation Sea Lion, the invasion of England was not something considered practical, or even possible, and wasn't considered at all in German pre war planning.

The success of the Blitzkrieg astonished the German High Command nearly as much as it did the Allies. The German High Command expected it to work, but were stunned by how well and how fast it worked.

Poland lasted a bare 26 days. Norway was invaded Apr 9th, and didn't officially surrender until June 10th, but was essentially beaten in a month.

The German attack on France and the low countries began on May 10th, the British were driven to the sea and evacuated the last week of May and into the first week of June, recovering some 330,000 men at through "miracle of Dunkirk", but leaving all of their heavy equipment, and a significant percentage of their lighter arms as well.

France surrendered on June 25th.

Essentially leaving the Wehrmacht in a "now what do we do?" situation, one they never counted on having, and particularly, so soon.
When Britain made it clear that an armistice wasn't going to happen, Hitler ordered plans to be made and resources gathered.

One point all the planners agreed on was that the invasion could not succeed without control of the air. IF the Luftwaffe could knock out the RAF, then German air and seapower stood a shot at neutralizing the Royal Nave enough to get the invasion across. But, without taking out the RAF there was no chance, so that was the intention of the Battle of Britain, to knock out the RAF, so the invasion could stand a chance of success.

They tried, and might have managed it, if Hitler hadn't changed his priorities from military ops to political terror bombings.

Although the British held the field (the common definition of winning a battle) it wasn't a win as much as it was a "not losing" and when things were clear there wasn't going to be a quick or easy victory, Hitler turned his attention, and the bulk of his forces toward the "real" enemy, the Soviet Union.

And got distracted on the way there, so things didn't go as forseen in Russia, either.

He probably expected England to "wither on the vine" and no longer be a threat, but things didn't work out that way, either.

Despite how much armchair experts make of the ineffectiveness of the 8 gun .303 British fighters, they scored heavily against the Luftwaffe, so, one cannot, in fairness say they didn't work.