Germany had hoped for a quick peace with Britain after defeating France, and then, when France switched sides. It was not to be.
Germany could field 2,700 planes, Italy, France and Spain a total of 3,400. Göring chose to avoid (as much as possible) bombings against civilians, he preferred to destroy the RAF by targeting airfields and factories.
The Battle of Britain would be a long, grinding battle of attrition, going on from August 1940 to February 1941.
Britain had one major advantage : downed British pilots and planes could often be recovered. However, the Axis also had a major advantage : they largely outproduced Britain, replacing their losses faster. So the attrition gradually favored the Axis.
Germany had another ace : U-boat wolfpacks. They were extremely numerous, being produced througout Europe and Soviet Union. Göring had outsourced production of Bismarck-class battleships and U-boats to the Soviets (who couldn't threaten Germany on sea anyway), in exchange for them getting the technology.
U-boat wolfpacks would, slowly, strangle Britain.
Other grim news for Britain were the fall of Malta and Gibraltar, thanks to coordinated Italian, Spanish, French and German efforts.
Morale was lowering in Britain.
