The simple answer is NO.
There is CPL theory and ATPL theory, they are two different (but not too different) theory papers. You don't need to do the CPL theory first (anymore).
If you don't plan on getting an IR, and just want to become an FI, do the CPL.
Otherwise, there is no point, and you may as well just do the ATPL theory. The exams remain valid sop long as you renew your IR at least every 7 years (don't let it lapse by more than 5 mind you, or you'll be paying the CAA another test visit).
Your choice
S