It is entirely possible to do the whole lot without a current class 1. However, the sensible way to do this would be to get your initial class 1 to ensure you can pass it, then fly on using the embedded class 2 privileges until the time comes to get your CPL, at which time you can renew it. You can even do the CPL skills test without a current Class 1 but you must have a valid and current class 1 for the CAS to issue your licence.