Chemin de la Liberté
Jerry Hodgson looks back at his crossing on the commemmorative walk in July 2012 here http://www.mirror.co.uk/news/uk-news/how-i-retraced-my-secret-agent-great-aunts-1180010
WW2 Esacpe Lines Memorial Society (Roger Stanton)
Esacpe Lines (Keith Janes)
There are several books available to help you learn about the route and the history that surrounds it.
The Freedom Trail by Scott Goodall. If you have difficulty in getting hold of a copy, try the publisher:
Inchmere Design. Tel: +44 (0) 1295 661000 Fax: +44 (0) 1295 277 939
Cruel Crossing by Edward Stourton which is easily available.