Currently at about half-way in reading “Operation Sea Lion” by a chap called Peter Fleming. Very good book so far. Doesn’t get embroiled in Battle of Britain stuff; it’s just talking about Sea Lion. Both the German preparations (or lack thereof, it seems!) and the British preparations and attitudes are covered. Very interesting to read just how unprepared the Germans were and just how late they left it before even realising they would need to invade Britain (Hitler being convinced they’d sue for peace). Also interesting to read just how over-cautious Britain was - keeping a big chunk of the Royal Navy in port ready to race to the invasion area, when in truth the logistics of the German crossings would have meant they could be doing a useful job elsewhere, say in the Western Approaches, and still make it back in time to foil an invasion.
Also mentioned was that the British gave the Germans more credit than they deserved as far as their preparations for invading Britain went. To begin with, they were convinced the invasion was going to come from Baltic ports to the East coast because the (more easily photographed) Channel ports were devoid of invasion fleets. In truth, this was because the Germans had barely made any plans for invasion by that point so hadn’t begun the build up! They planned to invade in the “traditional” place, in much lesser strength than the British expected (having overestimated the German’s ability and preparations for such operations, they overestimated the amount of divisions that the Germans could land and support… as had the Germans originally before the reality of their capabilities sank in).