A German-Soviet naval exchange and Britain's submarine threat

What if Germany and the Soviet Union swapped navies before the invasion of the USSR?

Britain would benefit from Germany losing its U-boats and receiving a less threatening surface force.

Neither Germany nor the Soviet Union is expected to welcome the exchanged fleet in this scenario. Britain would benefit from the change in its opposition. Soviet Gangut-type battleships are considered a much smaller threat in German hands, and Germany's loss of its U-boats would also help the British.