You can't have a successful operation sealion, unless you get Germany to start rearming back in the 20s. It is not just a matter of equipment, it is as well a matter of developing tactics and doctrines.
As a guideline in order to invade Britain you need an overwhelming airforce.
This assumes numerous PODs on its own: you need Luftwaffe to be created much earlier , and no bias from incompetent air marshals and the experience in the Spanish civil war. In hindsight Germany should have skipped useless heavy fighters like the Bf110 and built more Bf-109, upgrading them to achieve greater range, more Fw-190, slightly less Ju-87 (you need them, but not so many of them as OTL), and still build more Ju-88 and earlier, without useless requirement for dive bombing, and numerous naval bombers to gut the royal navy if it approaches contested waters.
But especially you need a huge fleet of strategical bombers.
I can never insist enough on this point: history has proven twice that submarine blockades are totally useless: for as good as you can be, you can never really strangle a big nation to death with submarines, and any achivement will always be temporary. OTOH if you can bomb the hell out of britain there is simply no point in controlling the sea lanes, if you can' build anything because your industrial base is razed to the ground and burning. If you manage to bomb the aircraft plants, the naval shipyards, the refineries and the ports you can wreck aircraft production, naval shipbuilding, fuel refining, importation of goods respectively.
As a bonus the psychological effect of Portsmouth or dover or London itself burning in a sea of flames is much greater than that of the ennesimal freighter ship sinking in the midst of the Atlantic.
So, that is, in hindsight, the opportunity the Germans missed: the introduction of the airplane means you can bend an island nation to their knees even without having a strong navy, an unprecedented vulnerability for UK.
But then again, in order to have Luftwaffe rule the skies you need several conditions:
A) start experimenting and developing loooong before 1935
B) realize the importance of strategical and naval bombers
C)have someone capable in command
D) possibly have Britain suffer from victory malaise and think the navy is all they need to be secure, so not to effectively counter a German air force buildup greater and longer than OTL.
Points B and C are easily manageable without derailing into ASB territory
Point D is a stretch but feasible. After all OTL Luftwaffe had a large advantage in numbers at the outbreak of war, and the British did not seem too worried about the fact, only starting to truly ramp up production of planes when the Germans started appearing in the skies of britain. By that time in an ATL whet Germany owns a large bomber fleet and effective fighters, it is possible that there are no aircraft factories left to ramp up anything.
Point A is the real problem: in order for germany to start exploring planes so much earlier you need a different outcome to ww1, and who knows what's going to happen then.