[grumble mode on] Wrong place for the thread, better in the what-if section. [grumble mode off]
Let's see, this would be a very complicated affair. First of all Germany would have to set up a very strong contingent in England to ward off the British forces now quartered in Wales, Scotland and Ulster, the rest of the United Kingdom. Expect strong forces from the entire Commonwealth (Canada, India, Australia, New Zealand, S.Africa, Rhodesia, etc) disembarking there, plus early entry of the USA in the war. Ireland would also be likely to chip in too, nudged by the USA.
Portugal would dust off the old 14th century treaty with England (still in force today), open up access to Azores and Madeira archipelagos for anti-submarine warfare, and mine the Gibraltar strait, locking Italy in. Spain would look startled but would respect the Iberian Pact.
In the meantime Stalin could very possibly decided to stop feeding the Fascists for peanuts in exchange, stopped his remmittances of foodstuffs and raw materials therefore strangling the German economy which at the time wasn't yet able to exploit the Grossraumwirtschaft (large space economy, i.e., plunder of occupied countries), and invade Romania while the Germans were occupied on the West, therefore cutting off oil supply and wheat.
On the whole, a briliant outlook.
