Britain's plans for invading Japan

Did Britain have plans to invade the Japanese home islands?

Yes. Blockade was the preferred approach, but invasion planning existed as a contingency and would have involved a very broad Allied force.

British planning against Japan had long leaned toward blockade rather than immediate amphibious invasion. Invasion plans still existed as a contingency because the war could not be allowed to continue indefinitely. Experience against defended Japanese islands, including Okinawa, made the expected casualty burden impossible to ignore. A later answer warns that parts of Japan's military leadership remained resistant even after the atomic bombings, so approaching invasion forces alone could not be assumed to compel surrender. By the Second World War, the projected scale of losses meant any invasion would have required a broad coalition of American, British, Canadian, Indian, Australian, New Zealand, and other Allied forces.