What an odd question! Well in theory you could start such a multi-pilot type rating course with a PPL, but only after you've done all this:
1. 100hrs PIC
2. Multi IR
3. MCC
4. Passed all ATPL exams
By which stage you'd probably already have a CPL!
Doing private charter work isn't as simple as just having a CPL. Commercial transport operations must be run by a company holding an Air Operators Certificate which is no simple thing to obtain.
flyer