The POD in this is that Hitler decides not to attack The Soviet Union, but instead he decides to launch operation green (the invasion of Ireland) Britain goes to Ireland's aid. Big mistake! While Britain is distracted, the Nazis launch operation Sea Lion (the invasion of Britain).
1941: Hitler decides not to attack the Soviet Union. He launches Operation green and invades Ireland. Ireland's military may be weak, but the Irish will not stand to be ruled by another outside power. They rise up.
Britain sends soldiers to Ireland. A lot of soldiers are now in Ireland. Hitler has his chance. Operation Sea lion beings. They quickly take over the south east of England. Soldiers in Ireland go back to Britain.
People in Ireland join the IRA to fight against the Nazis. They are no match for the Nazis.
Nazi forces go into London. A five-month battle in London begins.
1942: The battle in London is lost. Prime Minister Winston Churchill is reported to have been killed by a bomb. The royal family escapes to Canada by a thread.
Hitler asks the Japanese not to attack America, he is afraid that if America joins the war on the side of the Allies they may lose. Pearl Harbor attack never happens.
Dublin, the capital of Ireland falls to the Nazis. Hitler puts Ailtirí na hAiséirghe (a Fascist party in Ireland at the time. It's Irish for Architects of the Resurrection) in charge. An Irish puppet state is established. They then invade Northern Ireland.