I'd agree with wrk101, and guess that it's not P series. Though those lugs are throwing me off. Some simple upgrades will greatly improve things for you - alloy rims, high quality brake pads (Kool Stop make pretty and pricey salmon pads for mafac brakes).

If it's Simplex derailleurs check for cracks in the plastic. if you find any, replace them. Some also say that replacing AVA stems is urgent as they are prone to cracking.

Sheldon Brown has some pretty thorough info on french bike sizes etc. - google "Sheldon Brown French"

Upgrades can come slowly and you will connect with the bike the more you do. Enjoy!