A popular misconception, the heavy units were based in Scapa and Rosyth, but lighter forces (the ones that would do the real damage) were based in slightly closer places such as Portsmouth, Chatham, Dover, Harwich, Plymouth etc. The Luftwaffe had already demonstrated its effectiveness (or lack of) at that stage in the war against mobile ships at Dunkirk so daylight operations were not impossible and were in fact quite likely. The RN trained very hard for night actions having been caught napping to some extent in 1916 and were the world leaders (along with the IJN in the art of the night action - the result (as shown later during the campaigns around Crete) would have been a bloodbath for the Germans, and thats even before you consider the woeful inadequacy of their amphibious vessels.