What was the Britain’s long term war plan?

After the Allies’ defeat in Western Europe, Scandinavia and the Balkans, how did the Brits see their war prospects? Up until Barbarossa, all their allies on the continent had been defeated, and the only major friendly power overseas was the US, which while it was a critical supplier of war material, was hardly ready to actually join the war themselves. They had no major army which could challenge the Wehrmacht, and could barely protect their Mediterranean holdings. And even if they could defeat the Axis in North Africa, how would that get them any closer to liberating France or defeating Germany? At this point was Britain only in the war out of principle and hatred for the Nazis, or did they actually have any plan for winning the war?