What if Himmler took control of the Reich?

Science Fiction

Normal History of the World as we know it until May 5th 1941, When Adolfus Hitler and Joseph Gobbels is assassinated by the leader of the Schutzstaffel, Heinrich Himmler.
Heinrich then assumes command of the Third Reich and does not invade the Soviet Union and instead focus the resources of the Reich on an invasion of Britain.
By March 19th of 1942 the German War machine lands in Plymouth and starts the Invasion of Britain. The RAF (Royal Air Force) has been crippled by repeated Luftwaffe strikes on Military bases and Airfields. The British Army had attempted a maneuver aided by the Royal Navy in an attempt to retake Plymouth. It failed and 12,000 British soldiers were sent to there death, along with the sinking of a British Ship: The Ark Royal.
After this embarrassing failure the British armed forces fell back and secured a flimsy perimeter around the Cornwall region.
Then at the start of are tale, on the anniversary of Hitler and Gobbel’s assassination, the German Blitzkrieg has pushed the British all the way back to Birmingham, but with American support in the war the Germans have not been able to push the British into Birmingham.

No alterations to our own universe.

Technology from the 1940s