The CPL and IR exams are literally the ATPL exams
This is incorrect. There is a fair amount of material in the ATPL that is not covered in either the CPL or the IR, hence if you have CPL and IR passes and want an ATPL then you must do the ATPL exams.
The choice is to learn a little more and do the ATPLs or learn less but do more exams so pay more fees and usually take longer by doing the CPL and IR. Note the HP&L syllabus is identical, and all courses take the same exam, butyou will have to pass twice, because someone in authority can't do their job properly and the rules have been royally screwed up. I would do the ATPLs, as do most in your position.