Here's the dimensions you need:
** Greatest length 38.5 meters
** Maximum beam 5.0 m.
** Maximum draft 1.8 m.
** Maximum air draft 3.5 m. (ie bridge clearance).
Amazon has a book by MCKNIGHT which is widely used as the guide for the canals.
Amazon.com: Cruising French Waterways, Third Edition: Books: Hugh McKnight