Well this brings us to one of the big questions of the battle of Britain: how many serviceable aircraft of each type did each country actualy have in June 1940 ?
The French and lower countries campaign were very costly for the Luftwaffe, that lost over 2000 planes in a few months. Many experienced pilots were lost or were on recuperation after those battles.
This reduced the strength of the attack over the British quite alot. Moreover, Luftflotten 1 and 4 were not committed to the Battle of Britain, while Luftflotte 5 was based in NOrway and only had ~ 150 bombers and fighters available. This left Luftflotten 2 and 3 to wage the war... Some squadrons from LW 1 and 4 had been reassigned to LW 2 and 3, but we do not know exactly how many units did either Luftflotte possess. What is known is that a good number of gruppen from LW 1, 4 and 5 were in recuperation in Germany, while others were tasked with local defence of the lower countries.
Most sources indicate about 20000 - 2200 planes were serviceable for LW 2 + 3, out of which about 800 Me-109, 200 Me-110, and maybe 1200 bombers of all types (Ju87, Ju88, He111, Do17, etc).
The same sources indicate that the total strength of the Luftwaffe in june 1940 was around 2800-3200 fighters and bombers. If this is so, this means that at least 600, if not 1000 warplanes were not used during the battle for Britain ...
The RAF on the other hand had problems of their own - the French campaign had robbed them of hundreds of planes and experienced pilots. Most sources tend to indicate that the total strength of the fighter force was about 700 units in June 1940, with about 550 Spitfires and Hurricanes.
After the battle for France, Bomber command fielded some 500 - 600 serviceable and relatively modern bombers (Blenheim, Wellington, Halifax, Hampden, etc)
Coastal Command woudl add over 300 serviceable bombers, but most were obsolete Fairey Battles and Avro Ansons, and floatplanes such as the Sunderland, the London, etc. They had some 50 Blenheims though, which could add their hitting power to that of Bomber Command.
And we should not forget about the carriers of the Royal Navy.
If Britain were in a real invasion threat, the fleet carriers would most likely be sent to intervene.
In june 1940, the Royal Navy fielded Argus, Glorious, Furious, Eagle, HErmes, Ark Royal. In Aug, Illustrious would be added to the fleet.
In total, the 6 carriers fielded about 200 warplanes, about 100 Fulmars and 100 Swordfish torpedo-bombers.
So woudl the Luftwaffe be able to establish and mantain air superiority over the Channell and over the beaches ?
And would something change if the entire force of the Luftwaffe would be committed to this battle ? [LW 1, 4]