My understanding is the British Army lost almost all of its equipment in the Battle of France (excluding troops in the Mediterranean, and other overseas colonies). The evacuation from Dunkirk forced them to leave behind all of their artillery and tractors.
It would have likely been somewhat similar to a "Mega-Crete 1941" campaign, where the British army evacuated from Greece was overrun by German paratroopers with nothing but pistols (German paratroopers landed with main armament separate of operators).
That's... not a good comparison. Crete fell largely due to communication failures allowing the Germans to take the airfield unopposed on the second day. Despite operating with a weaker fleet in a much less favorable aerial environment, RN attacks forced the Axis to abandon naval landing and resupply attempts. Even in the best-case scenario the Germans wouldn't have enough paratroopers for a "mega-Crete."
Depends on what we're talking about. In 1940 they definitely did not, but due to weather/hydrology conditions, a naval invasion in Fall of 1940 was unlikely anyways.
As to capacity, they managed to pull of Norway 1940 in even worse conditions.
Again, we have Normandy 1944 as "Reverse Sea-Lion". Everything what you're saying can be applied to that operation, and yet the Allies succeeded (despite even landing in a coastally fortified area).
A naval invasion in fall 1940 was always unlikely and probably would have failed. On October 1 1940, Churchill told the King that "Hitler could and should have invaded this country after Dunkirk, leaving the advance into Paris until later. The French could not have prevented Germany from doing so" (Andrew Roberts,
Churchill).
Conditions in Norway were... pretty good, honestly. The Norwegians and Danes didn't believe they'd be invaded, and the Norwegians spent more time and energy warning the British away from laying mines off their coast than they did preparing for the Germans (William Scheier,
Collapse of the Third Republic). They also didn't pass on any of the warnings they were getting from their own intelligence services to either the British or the French. And French intelligence was so poor that Darlan, minister of the Navy, didn't learn of the invasion until Premier Reynaud read about it in Reuters and called him. The British, meanwhile, had serious command-and-control problems. Partly those were the responsibility of Churchill, but largely they were the fault of Neville Chamberlain's failure to set up unified chains of command and overall theatre commanders. Once Denmark had fallen and its bases became available, the Skagerrak straits were closed and Germany could use the Baltic as a private inland sea for resupply. Norway, frankly, was an easy campaign.
At the time of Overlord, the Allies had overwhelming aerial superiority of a kind the Axis hadn't enjoyed since early 1940. On D-Day, the Allied air forces flew more than 13,000 missions; the Luftwaffe, fewer than 350. The Allies had overwhelming naval superiority; more ships were engaged in bombarding the French coast than the whole surface fleet of the German prewar navy. By 1944, German forces were engaged on three fronts: preparing to receive an amphibious assault on the coast of France, fighting in Italy and on the eastern front. Germany was without substantial reserves of a high quality. Maybe most importantly, the Allies had a tremendous logistics advantage by the time of Overlord compared to what the Germans would have had in 1940. Throughout 1943 and 1944, the British and Americans spent millions of dollars building railroads to beaches, storage sidings, fuel and munitions storage facilities and hard road networks in southern England. Most importantly, the Allies had much more shipping and naval transport capability available in 1944 than the Germans had ever at any time. Overlord was not, in any important way, "a reverse Sealion," an operation which depended on a suprise cross-Channel attack in bad weather and lightning speed to capture important objectives.
Somehow Germany launched the Norway naval invasion, landed navally (besides paradrops) at Crete and the British navy couldn't stop them. Not only that, from 1940 to 1945, they had no issue supplying Norway by sea. Why they would suddenly not be able to supply a force in the UK from French ports from a shorter distance, I have trouble understanding.
See above -- the Skagerrak strait was closed and the Allies had no available airbases. Norway tells us nothing about an action in the Channel. And what Crete tells us is that landing naval forces without overwhelming local naval superiority doesn't work.
