There was never any serious threat of an amphibious invasion. The capabilities of the Kriegsmarine for that were woefull (even the army &the Lufftwafe balked at the idea). No such invasion could even be considered unless the RAF was knocked out the Royal Navy kept from the invasion beachead (an imposibility). The German Navy had no hope of ever defeating the Royal Navy in a shootout. It was also not possible to build up its fleet quickly. The German Navy believed that by 1946 they would have had several more BISMARK class Battleships and several aircraft carriers.