I converted mine a few years ago (but was CAA not JAA back then). I had 43hrs Air Squadron, and ended up doing about 1/2 a PPL eg) 20hrs, ground exams, GFT / NFT. You will probably need to send your logbook to CAA FCL who will do an assesment and tell you exactly what uou need to do.
Give them a call, if you can stand holding on the phone for a while they are very helpful! (LASORS on the web may have the answer too).