Quote Originally Posted by Kagemusha
But Seamus if the Germans would have had month to build blockade on end of Channel and the Coastal batteries would have been in their use
Don't you think the British would have used the time productively as well? Remember the British were actually outbuilding the Germans in planes as this time, and the attrition was steadily in favour of Britain despite more experienced Luftwaffe pilots as German pilots who bailed out over Britain were captured and those in the sea weren't recovered, unlike British pilots who lived to fight another day. And when you say that the Germans would have built a blockade at the end of the Channel, how would they have done it? British warships were situated everywhere, and the relatively unharmed 12 Group was north of the Thames, while the south coast absolutely bristled with defences in depth.
How many ships from Mediterranian fleet could have passed in the channel.
They'll need to pass Gibraltar first. Also, which Mediterranean fleet are you talking about? The French fleets that were severely damaged by the British at Mers el Kebir and Oran and whose remnants were later scuttled by their crews? Or the Italians? In which case The British Med fleet would say thank you, stock up Malta with supplies, and ravage the Italian coasts. If the Italian fleet was lucky enough to pass through the straits into the Atlantic, they'll have to run the gauntlet again as they're recalled to defend against Cunningham's fleet running riot in the Mediterranean. Considering Mussolini's reluctance to risk his precious fleet within the Mediterranean, it's hard to imagine him sending them beyond the bottleneck of Gibraltar into the north, leaving Italy defenceless against a powerful British fleet in the Mediterranean.
Also once the Both shores would have been in German hands why use barges when you can use merchant ships?
Merchant ships from where? In what numbers? How would they be defended during the crossing? How many would be left for the repeat crossings necessary for resupply, even if we assume that a sizeable force could be landed in the first wave?

I get the impression that many people regard Sealion as an RTW game, where an army can be dumped on the shores and left to campaign until victory. A modern army needs supplies of all kinds. The British army during WW2 had I think 4 men in non-combat services for every 1 in the front line, ensuring that the army ran smoothly. The ratio was similar in the other armies.

Read the links in the earlier posts for a fuller explanation of the problems with Sealion and any other prospective invasion of Britain.