"I think the RAF missed an opportunity here especially if all the invasion barges had gone so those didn't need bombing. IIRC the Luftwaffe carried out limited intruder operations againt the bomber fleets over the UK with some success though of course their aircraft were fitted with radar."
If I may correct a couple of factual errors?
Although the barges had left, the RAF were kept busy mining the ports and coastal sea route to prevent not only the Germans moving in another invasion fleet but also to counter the U-boat threat. Secondly, the German intruder operations were not that successful in kills although they proved a considerable nuisance. In fact, German intruder losses were about the same as RAF losses (quite a few were lost in transit). Hitler had forbidden radar equipped intruder aircraft from operating over allied territory to stop secrets falling into allied hands - and he soon stopped intruder operations totally. Despite Kammhuber stating that "if he wanted to kill wasps then he would swat them en-masse in their lair", Hitler wanted the German people to see burning bombers on their own soil to show that Germany was defending against the bomber offensive. The Germans were also very short of fuel - especially after the invasion of Russia and Hitler considered the transit to UK by night fighters as a waste of petrol. After that, there were only limited non-radar equipped small offensives later in the war - principally by Me-210 aircraft. The final German night-fighter offensive was at the end of the war when Hitler made a final gamble and unleashed his radar night-fighters over the North Sea after the returning bomber stream with Operation Gazelle. Many tens of bombers fell victim although a good few night fighters were also lost.