Doghouse has said exactly what I haven't got round to saying yet!
I'd forgotten about the CPL instrument flying which would be tough without any previous experience. Best to get the basic instrument skills earlier than burning big money on a complex type with a CPL level instructor.
As an aside, the old UK CPL gave IMC rating privileges, even if you'd never done the rating before. That's why the the CPL test here still includes some instrument flying. However, the JAA CPL gives no such privileges. Pay more, get less... good eh? An examiner told me a change to the CPL test is planned to remove the instrument requirement. No idea when though.
Another thought to consider: if you took your JAA IR before the CPL then you're credited with 10 hours CPL instruction, reducing the CPL training to a minimum 15 hours visual flying.