Put on the kettle and grab a comfortable seat and plan on spending a few days doing a bit of detailed research into your chosen profession. Start by looking at the stickies at the top of this forum and then download a copy of LASORS from the UK CAA website.
In the latter document you will find lots of information about the privileges of a CPL (with the JAA CPL exam credits) vs those if you had passed the 14 ATPL exams and then undertaken a CPL and MEIR.
A bit of research now will save you a load of heartache and cash later on if you don't follow the right pathway.