So basically I was not too far from the truth saying that meeting a E-7 in the BoB was as likely as meeting a Spitfire Mk.Ib
30 vs. 32 pieces and that information is for January.
E-4/Ns also listed in January at 54 pcs, one Gruppe of JG26 used them quite early, that might be cca 40 aircraft in the Summer already (makes sense). I guess Perez's aircraft was part of this Gruppe. It seems that 100 octane fuel and 601N engines were more relevant for Bf 110s Squadrons in the sim. In the actual Battle of Britain, these subtypes were present at rather marginal numbers - at 31.8.1940 we've got 871 Bf 109s in service, let's say some 1é or less % were fighters with DB 601N.
Same with droptanks coming in November - this is very important for next stage of the war (the Blitz as the British call it).