Unless you are sure you want to go multi crew (eg North Sea) the CPL(IR) is sufficient, it will save you an awful lot of studying aeroplanes on the ATPL theory (yes its all fixed wing) dont worry about the 7 IR exams if you run out of time for the IR (3 years) they are a piece of cake, you can do them in around 4 months. (yeah I had to do them!)
Regards,
BC.