The Luftwaffe was never going to win - Full Stop.
Bombing radar stations or the airfields - could degrade the RAF's response but not beat it.
If the RAF ever was under pressure they could withdraw (unbeaten) to North of the Thames (109 range) and reform.
The Germans could never have sustained a landing on the UK - RN 15 Battleships - Kreigsmarine -0 Battleships.
The few was not the last line of defence but the first.
I think the propaganda of the time has created a myth that does not stand up to the reality.