I took England in 1940 right after France. Taking England was in my planning since 1933. I created a force of 12 marines and 6 Paratroopers. Plan Z really helped, but I also built up a fleet of transports and some more capital ships. Being allied with Spain gave me their Navy to serve as a decoy fleet which helped draw off England's huge navy.
With their navy drawn off chasing the Spanish Fleet around Spain, I deployed screens of Battleship groups closing off the channel and near Scapa Flow to keep their Navy from my landing force. I used three groups of 3 marines and conducted invasions on the northeast side of England. I had another group coming from Iceland on the western side if their Navy wasn't present there.
I dropped Paratroopers next to some of the provinces I planned to invade with Marines to keep them from reinforcing. The moment I made a beachhead I brought in regular reinforcements, probably about 15 infantry divisions and a couple armored divisions. After I had several beach heads I started to pocket their Navy and picked them off with bombers and some of my carrier battle groups. After this England was a cakewalk.
Gibralter was taken during my France campaign after I allied with Spain. Suez was captured very shortly after England after I deployed some infantry from Italy. Once Suez was taken England surrendered and switched to a Facism government. After a couple of diplomatic influences England was in my Alliance.
With England in my alliance the world really changed. France and her allies had a ceasefire and I could concentrate on Russia.
I thought at first that I might have handicapped my self focusing on an invasion style military, in other words I didn't have very many armored forces. But with quick enveloping maneuvers huge pockets of russian troops were wiped out so it worked out.
Hope this helps.
