He offered them favourable terms if they surrendered...
Hitler didn’t even want the Brits to surrender. He wanted to make peace with them.
The Germans would take Europe and probably North Africa and the Middle East.
The Brits would take everything else.
Together the Aryan Germans and Brits would rule the subhumans of the rest of the world.
This was so thoroughly worked out in the Nazi ideology that they were absolutely astonished when the Brits had no interest in going along with it.