We were lucky - the Luftwaffe was designed to support the Army in the Blitzkrieg....not support an amphibious invasion of the UK......however, that doesn't mean it couldn't have happened.
We were also lucky in that the Germans intelligence wasn't up to scratch, a case in point being the 18th August, where the afternoon attacks that massively damaged Gosport, Ford and Thorney Island airfields were seen as successful, despite their losses as they didn't realise these were FAA airfields not RAF ones.....but the mauling StG.77 suffered in the attacks on Ford and Thorney ended the much vaunted use of the Stuka in the BofB, and they were not used again in a mass attack on the UK mainland.
18th also ended the low level attacks as per that of 9th Staffel on Kenley after the few crews that got back were debriefed and the incredulity of the Germans at the success of the Kenley Parachute and Cable device against the low flying Do.17's.