Bad weather preventing the naval operation is probably the best outcome, maybe Germany comes out ahead on aircraft losses in the build up to it, and picks off a few destroyers and cruisers raiding the french coast.
But from a ‘success on the ground’ point of view there is this...
The Germans land and manage to make headway for 24-48 before the Royal Navy and RAF closes the channel. This assumes it takes time for the UK to build up an overwhelming naval operation that crushes all before it in a glorious and cost effective manner. The invaders struggle to take more than one small port and a few towns, the heavy presence of home guard and regular formations mean they never really make it far from the landing areas. British losses in combat are heavier as they are initially more static, but once much of the invasion force is then forced to surrender the maths looks grim.
In a previous thread some years ago it was pointed out that the German plans would require 48 hours simply to form up the barge lines on the French side, some of which would take place in sight of Dover on a clear day. If it only takes 24-48 hours for the RN to close the channel then it's very possible nobody will make it across at all.