The crucial point is that Churchill - opposed by some who were ready to make terms with Germany - led the nation in fighting on, and resisting the invasion that everyone expected was inevitable, because since 1939 the Germans had seemed invincible.
The RAF handed the Germans a tactical defeat - since the Germans did not accomplish any of their objectives (whether to invade, to achieve air superiority over south-east England, or to destroy the RAF as a fighting force) and the RAF achieved its objective, which was to retain control of the air over England. I'm not sure how you call that a draw.
Whether the invasion would have been possible even with German air dominance over the Channel is an unanswerable what-if. Peter Fleming, in the 1960s book Operation Sea Lion (based on wargames if I remember rightly), concluded that the OKW was planning what was essentially a river crossing under fire and could not have successfully held ground in the UK.
What's more important was that the Battle of Britain proved that the Germans could be beaten. This in turn proved Churchill right, and the Halifaxes and Kennedys wrong.