Thanos Thanos:
Yeah. The German air assault was too haphazard to eliminate the RAF. Let's say they concentrated on destroying the radar stations first. Early technology in set locations, not portable, can't be replaced quickly. That rips open a huge hole in detection over southeast England. Then hammer the crap out of the RAF airfields. This starts to take the RAF out through attrition. The time comes soon when the RAF reaches it's breaking point and is no longer effective. No RAF means that the Germans can then start pounding any Royal Navy assets in the area because they already proved during the Dunkirk evacuation how vulnerable ships are to air attack. Plus you then have Bismarck, Scharnhorst, Gneisenau, and the rest of the bigger Kreigsmarine vessels make an appearance in the North Sea to keep the Home Fleet stuck in Scapa Flow and unable to head south to the Channel. Then the inevitable happens when about ten to fifteen thousand German parachutists and glider troops land and take over a port city like Dover. The regular British army is still whipped from what happened in France to the point of being irrelevant and only a lunatic would think that Dad's Army would make even the smallest dent against hardened Wehrmacht soldiers. Then with a port secured and the RAF and Royal Navy no longer an issue, the Germans can then use standard container ships and barges to ferry panzer units and the bulk of the Wehrmacht infantry across the Channel in a corridor that's solidly protected by the Luftwaffe and the U-boats. The Germans are then able to rampage across England the same way they did in France or, more likely, the British government capitulates. Churchill and the Royal Family flee to Canada and a pro-German puppet government is installed in Britain the same way it was in Vichy France.
It would have been the toughest and most risky campaign the Germans attempted but it was plausible. Change a few of Hitler's personal whims, like pointlessly reaching out to Churchill for an armistice after France collapsed, and have a solid plan in place even before the invasion of France and knocking Britain out of the war was certainly doable.
Actually, the RAF was pretty close to being on its knees until the fickle finger of fate intervened. The Germans WERE bombing the radar installations, as well as airfields and aircraft manufactories. That was the plan and Hitler was sticking to it. In fact Hitler had forbidden any attacks on London proper. However one fateful night a lone bomber crew got lost in the smoke and haze and were running short of fuel. They decided to drop their load which happened to be when they were over London proper.
Outraged by this act, the RAF mounted a 12 bomber raid on Berlin the following night. Hitler, unaware of what had transpired the previous night, lost his shit and lost sight of the ball, changing the bombing campaign to attack the City of London. This gave a HUGE reprieve to the RAF who could repair their radar stations, fill in all the craters on their airfields, all while aircraft production increased. One lone, lost bomber crew quite possibly changed the fate that Britain was staring at.