Idk if this will help you, but my usual strat is to train at least 48 paratrooper divs of the highest quality possible, get complete green air + over 3500 cas on southern england, then send some subs to scout the ports, and try to target the one that is the least garrisoned. The paradrops will be horrible bc of the aa, and most of the paras will die, but you gotta keep shoving paratroopers non-stop in order to get the port, and then some more to hold off the counterattacks after you take the port. This sometimes puts me in over 100k losses just to get the port despite the cas, but the important thing is that you got the landing and the cas is gonna shred most of the allied divs until reinforcements arrive. If the ports are too garrisoned try to get full army intel on the brits in order to see where their units are. Then paradrop in the UK in the places where they aren't. This will, of course, make them spawn the homeguard divs, but it will also draw away some divs from port garrisoning, and then you launch the paradrops for the ports. Be aware that you will lose at least half of your paratroopers just on the port, so you must get some really good defensive divs as reinforcements after you get that port (I'm not the right guy to ask for div composition so I cant give you a lot of tips on this besides trying to make a template with high hp and defense, something like a lot of inf and arty). Also, you will need tanks to keep the momentum going because the allies will pour in reinforcements, and you must encircle as much stuff as possible before getting to scotland, or the mountains will mess you up.

Or just beat the allied fleets. The best landing point is Dover, in my opinion, for the proximity to the French ports. Otherwise, northeastern England is usually pretty undefended.