Bonjour cher ami
As 3000psi said, JAA licenses are a bit of a complex business
The only thing I know about it, is that the JAR CPL I was given by the CAA is virtually the same as the CAA CPL, except for a couple of words added... And a consequent fee, 172 £
Even if some countries like France won't consider your brand new JAR License, some countries, not necessarily members of EU; will accept it (Switzerland)
If you are looking for a job outside UK; it worth the fee to get new horizons