Surviving was all it had to do As I noted elsewhere recently - the "Small Island" thread IIRC - the "invasion window" in 1940 was remarkably short from the Armistice until safety for the rest of the year. Only 14-16 weeks from the Armistice with France until weather made it impossible until the Spring of '41.I would suggest that the RAF did more than just survive until the weather saved it.
But aircraft were never the problem....pilots were. Sheer numbers of aircraft was the wrong criteria, the one that Churchill and "Beppo" Schmid counted LOLthe number of new aircraft being produced was outpacing Germany, even as irrecoverable crew losses were lower. The Germans, by contrast, were in the reverse circumstance
And Dowding didn't actually set about creating a cohesive ASR capability until quite late in the summer, the Luftwaffe and its seaplanes had a great jump on us in that respect...around the time he ordered that fighters not intercept the incoming enemy until over the coast of England because of the irrecoverable loss rate. Until then, the RAF bled trained aircrew.
"Confidence" is indeed one of the issues. The Luftwaffe had the confidence that their "new" tactics would work if they'd been allowed to continue with them. The big day battles over London look as if they SHOULD have filled the RAF with confidence....but it wasn't all in their favour. For example - Douglas Bader's "Big Wing" got jumped on one occasion over London, with the two squadrons making it up getting badly cut up.Only the RAF was in a position to continue the Battle of Britain with confidence. I would suggest that the Germans needed the rest more than did the British.
The problem wasn't "total strength" of Fighter Command...except when the number of aircrew plummeted. because the number of fighter aircraft in the air that the Dowding System could handle on an ongoing basis was limited to c.740-750 in the entire country anyway...It ended the battle with a fighter strength numerically almost as strong as it started it
And further down the "System", the reason for the division into Sectors within groups is that in the period of HF radio, a "Sector" could only manage four squadrons at once; the number being limited by the number of radio channels it could use.
(That was one of the major complaints raised against Bader; in taking his squadron down to the coast "Jerry hunting" instead of protecting the airfields they were supposed to protect, he overloaded the radio net in that particular Sector, and the Sector Control Room couldn't control all its own aircraft it had in the air!)