And what of the 6,800 mines the Germans would have sewn to protect the invasion route ... or the fleet of 10 destroyers, 20 torpedo boats, 40 motor torpedo boats, 90 or so patrol boats, 100's of mine sweepers / layers, 27 U-Boats ... or the 6 batteries of super heavy naval guns (30 guns in total of 170mm to 380mm), the 42 heavy and medium batteries (probably of limited use but still ready to fire when needed) ... or the torpedo and dive bombers of the Luftwaffe?
6800 mines is something on the order of 3-4 mines per mile of invasion route - the invasion plan had landings spread all over southern England. Even if they picked one end of the channel and mined it "heavily" 6800 mines is on the order of 500 mines per mile of channel spread over any depth of mine field it is a risk but not huge. That's a minor nuisance not a minefield that would keep the British out.
10 destroyers, 20 torpedo boats, 40 motor torpedo boats, 90 patrol boats, 100's of mine sweepers/layers and 27 u-boats. Okay, first 100's of mine sweepers? What is your source on this? The Germans had fishing boats that they called mine sweepers, but dedicated mine sweepers? I am skeptical of this. What is the difference between torpedo boats and motor torpedo boats? I think you are double counting here. Maybe they had 60 E-Boats maybe. 90 Patrol boats - if they count fishing boats that make patrols maybe.
Take this against what the British are documented to have in the channel at the time targeted for the invasion. 79 Destroyers assigned to the Channel, 8 Cruisers, 68 mine sweepers (actually designed to be mine sweepers), in addition "many corvettes" which are larger than MTB's but smaller the Destroyers, 1 Aircraft Carrier, 2 Battleships, 1 Battle Cruiser escorted by 3 anti-aircraft Cruisers and a Destroyer flotilla.
The above is just what is actually in and around the channel, the rest of the home fleet is within 12-16 hours of arriving. And that included 5 more Battleships, 3 more Cruisers, and 9 more destroyers.
There were also 25 submarines but they would be unlikely to be used.
Don't forget the RAF, they have the unengaged wings from the north of England that were planned to be pulled into battle when the invasion was sighted. So the Luftwaffe would be outnumbered and fighting fresh defenders.
As for the torpedo and dive bombers that you refer to above, bombing warships is much different than bombing merchant ships, which was the experience that the German pilots have to this point in the war. The British would loose some ships but the RN is fighting off an invasion they would be willing to expand ships to win.