They certainly weren't towards the end of the battle.
The beginning is another matter. On 10 July the RAF had 570 operational Spitfires and Hurricanes. The Luftwaffe had about 1,100 operational 109s and 110s.
The RAF wasn't outnumbered in the beginning either. Now, usually the Hops like to quote strenght figures for the RAF at the beginning of July, and of course count only British single engined fighters while 110s are 'naturally' included.
But that was hardly representative of their relative strenght, since Fighter Command was rapidly expanding at the time, and, the Germans didn't start the Battle proper until mid-August. In specific number, although only 871 fighters were present with RAF fighter squadrons (644 being ready for ops), in just two weeks, by 20 July there were 1052 British fighters, altough the number available for ops remained pretty much the same (658).
Of course during July 1940 not much happened, ops were largely limited to small skirmishes, with light losses - the Germans for example reported just 34 Bf 109s and 19 Bf 110s lost to enemy action during the whole month. In August, when they started the battle proper, the figures were 177 and 114.
When the Battle started, there was pretty much parity between the number of fighters on both sides.
The Germans weren't committing all of their strength against Britain, either, although Hop quotes figures
for the entire Luftwaffe (including that in Germany and elsewhere not taking part)
The number of fighters employed against the British Isles on 10th August, when the Germans begun to launch serious operations, was 805
servicable Bf 109s and 224 servicable Bf 110s, out of a force of 934 and 289, 1223 in total "present" (ie. both servicable and unservicable aircraft). The 110s weren't all used as fighters either, as they often acted as light bombers.
Against this, the British reported, on the same day, 1106 fighters present, out of which 749 were serviceable, mostly single engined fighters.
By 7 September the RAF was up to 620 operational Spits and Hurricanes, the Luftwaffe down to 770 operational 109s and 110s.
Even then, though, the Luftwaffe was pretty much concentrated against the SE of England, whereas the RAF was spread over the UK.
Not all of the LW was flying every day, either. Units were rested from operation in the same manner as RAF Sqns, its only that they stayed at their base, and didn't transfer to the safe backyard as RAF Sqns did; the LW airfields in France were much less exposed to the RAF than vica versa.
In any case, the British doesn't seem to have been outnumbered at any part of the Battle, even when their situation was the worst in the first week of September, the British flew some 5513 fighter sorties against 2355 German. British bombers flew 642, Coastal Command 921 in addition, while the Luftwaffe's bombers flew 2855.