Dave:

Try the following titles are available at amazon.co.uk:

"U-boat War Patrol: The Hidden Photographic Diary
of U-564" by Laurence Paterson

"Wolf Pack: The Story of the U-boat in WWII" by
Gordon Williamson

"Hitler's U-boat Bases" by Jak P. Mallmann Showell

"War in the Boats: My WWII Submarine Battles" by
William J. Ruhe

"Red Star Under the Baltic: A Firsthand Account of
Life on Board a Soviet Submarine in WWII" by Viktor
Korzch

"The U-boat War: The German Submarine Service and the
Battle of the Atlantic 1935 - 1945" by David Westwood

"Unbroken: The Story of a Submarine" by Alistair Mars

"Final Patrol: True Stories of WWII Submarines" by
Don Keith

"Silent Running: My years on a WWII Attack Submarine"
by James F. Calvert

Freddy Suhren - Ace of Aces: Memoirs of a U-boat Rebel"
By Teddy Suhren

These should keep you busy for a while........

Regards,

ROBERT M.