A surprise German fleet on the eve of war

What if Germany gained a competent fleet equal to 75 percent of the Royal Navy one month before the Second World War?

Germany would face huge logistics and oil problems, while the Allies might react with panic building and possibly pre-emptive attacks on the fleet in harbour.

The immediate German problem would be sustaining the ships with crews, fuel, bases, and supply arrangements rather than simply owning more hulls. A fleet appearing only one month before war would have little time to create the institutions and operating system needed to use it coherently. Britain and France would answer with emergency construction and might decide that the new concentration had to be destroyed before Germany could solve those problems. The panel imagines bombers and carrier aircraft striking ships in harbour, turning the scenario into a race between German mobilisation and Allied pre-emption.