Steve,
The interiors of both subs can be toured.
Both have good websites:
For the Bundesmarine U-10 in the Marinemuseum in Wilhelmshaven, see:
[www.marinemuseum.de]
(and also see the Kriegsmarine minisub "Seehund" there)

For the Soviet diesel (non-nuclear) sub in Hamburg, see:
[www.U-434.de]
A good overall trip may be Wilhelmshaven (Bundesmarine U-10), then Bremerhaven (Kriegsmarine U-2540 which became the Bundesmarine U-Bauer), then Hamburg (Soviet sub), then Laboe near Kiel (U-995).
Good luck,
Hans