You need a public cat C of A for training and the aircraft would also need certifying if you were going to use it for a CPL test. You also need some complex time, so that might also preclude the idea. IMO, I reckon using your own a/c for a CPL is probably not economical.
If you're hours building - why not buy a PFA type outright? March PF magazine has a Jodel for £6500. Nice little aircraft and you could probably sell it for the same money if you didn't want it after the hours are built. You can have it all to yourself too for that price!