AF330,
Quote by Amadis of Gaul:
I'm sure there are plenty of books in French on engines in general, never mind turbofans. Starts small, then go big, the big isn't going anywhere.
To add to the suggestion Amadis made, just outside Paris on the A6, Exit E50, are two jet engine companies. CFM International has their main engine assembly plant there. SNECMA, who are half owners of CFM International (the other half is owned by GE), have offices and engine assembly facilities there as well. SNECMA's Evry-Corbeil address is:
10 Allée du Brévent 91019 Courcouronnes
+33 1 69 87 09 00
snecma.com
I think if you contact them, they can provide you with information to help you. If you explain to them your age and your dedication to understand and learn about jet engines there could even be more opportunities besides written information.