If you intend to take up flying as a career then I see little point in dong the CPL exams since they are not easy and comprise 90% of what you need for your ATPL exams. Sit the ATPLs straight off and save yourself alot of work in a year or so.
Even after gaining your CPL with the ATPL exams and an IR you will still only have a CPL...NOT an ATPL. Some call this a Frozen ATPL since when you have the required experience you can apply for the issue of an ATPL, there is no such license as a Frozen ATPL however.
Good luck!