First of all if you want the milk cows and the base at Vigo you need th IUB mod 1.02 and I use the clear water mod with it so you can see underwater better. Its really good. I am in 1940 in April and have the Bessel at Vigo and Thalia at Cadiz available for resupply of My U-boat its really good and in the map shows the Convoy routes to help you out. You should really like this mod.
this is what i use.
Kriegsmarine Capital ships Mod
Sh3 Commander mod
IUB 1.02 mod ( or Improved U-boat Mod)
Wolfies TweekPak
NSS_Uboat7c_No_Camo
Sink them all v2.2
and WaW 1.4 JS