I like this.

If i was not constrained by material shortages. After thinking about this for some time i would have gone for a fleet of at least 100 heavy class ocean capable destroyers, 140 U-Boats, 20-30 Surface Raiders (Kormoran type), 10-20 Pocket Battleships/Heavy Cruisers. I would not waste my time on the large Tirpitz class and Graf Zeppelin class of ships.

I would have prior to the outbreak of war deployed at least

40 Heavy class Destroyers.
40 U-Boats.
8 Surface Raiders
5 Pocket Battleships/Heavy Cruisers

Into the Med and have them based in Italy. This is to work with and assist the Italian Navy in taking on the Royal Navy from the ouset, sorta like preemptive strike at Alexandria.
As for everything else i'll think about it.