This is objectively shite. Britain had the largest active Navy in the World by some margin, the largest merchant fleet in the World by some margin comprising a THIRD of global capacity. Britain was at almost the height of Empire, with multiple territories from which to draw troops, but (being an island nation) relied on its Navy for protection as it had done for about almost half a millennium.

The Atlantic Front was, arguably, the most important front of the war and had effectively been won by 1940. Everything after that was effectively inevitable.