Okay, let me explain this scenario more fully. Germany, let say a Fascist one for now, rather than primarily having the goal of invading the Soviet Union(read: Hitler's over all goal), it instead directly all its efforts towards conquering the United Kingdom.
Why? I don't know, perhaps they decide to only go after the Entente powers that directly benefited from the Versaills treaty(minus Japan perhaps). Point is, what would happen if Germany directed all its military efforts, to conquering the United Kingdom? Will it never cause anywhere near what WW2 did? Or will it perhaps actually be able to hurt the United Kingdom significantly?