Yes indeed. I remember that discussion which was countered by the observation that the bulk of the RN were tucked up in Scapa and would have taken days to get to the Channel area - by which time the Germans would have already established coastal bridgeheads and inland pockets of fallschirmjager or have experienced failure after being repulsed by RAF and Army opposition. Upon their eventual arrival, the RN role would have been to try and prevent supply by sea to the invasion forces, but they would have been subjected to the Luftwaffe onslaught which they had previously wisely avoided by being up in Scapa and not berthed along the south coast.
Luftwaffe air superiority was paramount of course before any cross-channel incursion whatever the chances of success and that was denied to them.
'Find your enemy and shoot him down - everything else is unimportant.'
I remember that discussion which was countered by the observation that the bulk of the RN were tucked up in Scapa and would have taken days to get to the Channel area - by which time the Germans would have already established coastal bridgeheads and inland pockets of 
the RN role would have been to try and prevent supply by sea to the invasion forces, but they would have been subjected to the Luftwaffe onslaught which they had previously wisely avoided by being up in Scapa and not berthed along the south coast.
