There's quite a lot of info on similar topics around this forum so taking a bit of time to search around will help
In summary, the PPL is not really "part" of the CPL but a standalone qualification. For the modular route, you need to first get a PPL, then build experience until you have 150 ish hours. At that point you can start the ME, IR, CPL courses. Having the PPL won't shorten your CPL course but it is a mandatory part of the process of getting one.
The exception to the above is on an "integrated" course where all the training is completed in one go. In this case you will only sit the CPL/IR exam but the hours requirements and format of training are largely the same.