Why again are we expecting that Luftwaffe gaining TEMPORARY air superiority over discrete areas of SE England would allow them to execute Operation UMSM? As far as I remember, the barges would take two days (full 48 hours) to arrive at their destinations.
50% sink just so. Without any interference, or hostile action at all. A large number is sunk when the RN destroyer in high speed run during a night passes by. Note 'the' as in a single destroyer would probably suffice to send much of the abysmally slow and unseaworthy armada to the bottom of the Channel. Without ever firing a single round. The remaining (if any) that arrive to unload their troops encounter a hot welcome committee, and half of them lands sideways, complicating both unloading and returning, although already by this moment it is clear there will not be a second wave.
Finally, battered, seasick and exhausted soldiers that miraculously manage to emerge on the shore of Britain are unceremoniously killed or captured by British regulars and the Home Guard.
Germans lack the capability to capitalize on their potential air victory, even if it was at all possible. BoB was fought on a parity in numbers (of fighters, to be exact) and the British even if they were in danger of being defeated had even or better than even chances to emerge on top. By that time they already started to outproduce Germany in airplanes. They had the force multiplier in the form of well developed and applied integrated air defense system. They had overseas and US to supply with anything their industry lacked or couldn't produce.
For that matter, if the Allied experience over Germany is taken into account, industrial capability of a country is remarkably resilient. The Germans would need at least a year of total or near total air supremacy over the UK (the entire UK) to start making a dent in British production. Germany lacked airplanes and the method to achieve this. Quite aside of their intended next step in the project "Let's ruin Germany and Europe for years to come". Eventually, United States industrial potential comes to play and after that the writing on the wall is clear. Even without the Bomb.