Many of you will probably have seen this before but for those who haven't, here's a well written page on the various bases on the Atlantic French coast and their history.
It includes info on the u-boats stationed at the various bases as well as the building of the huge U-boot bunkers.
The page isn't complete but is worth a read. Check out the link at the bottom of it to see modern pics of the u-boat pens.
http://www.uboatwar.net/Fruboat.htm#Lorient