Oh we know, the German plans for Seelowe are open source now. Germany viewed the Channel as a large river. There was no plan for surface gunfire support, no specialized tank landing ships, the "landing barges" were converted river barges that weren't very seaworthy and the English Channel is one of the roughest bodies of water on the planet. Many of the barges weren't even self-propelled but would have to be towed by tugs or fishing trawlers. At best the Germans would have landed two infantry divisions and a hundred or so tanks, at worst, none of them would have survived the attacks by the RAF, Royal Navy cruisers, destroyers and corvettes based in or near the channel and the weather. Hitler would have lost his entire navy fighting the Royal Navy trying to clear the channel and protect the barges and all the troops. Even if Germany had managed to land the entire force, most of the barges would have been damaged or stuck on the beaches so there would be no resupply leaving the troops with whatever supplies and ammo they had on their backs. That would have been two or three days of combat at most. In eight hours, the tanks would have been static pillboxes when they ran out of fuel and drained the few service stations they might have captured intact. If the BEF hadn't escaped from Dunkirk with a large portion of the French Army, things might have been different since most of the trained British troops were in the BEF.
In short, the Germans had nothing that was necessary for a successful amphibious invasion, no training no equipment and no navy to speak of.