I can potentially add IRI / IMCRI onto my CRI
No you cannot. IRI is a separate qualification and if you do not hold a FI rating, then you would need 800 hours under IFR before you would be eligible to take the IRI Course.
FCL.915.IRI IRI — Prerequisites
An applicant for an IRI certificate shall:
(a) for an IRI(A):
(1) have completed at least 800 hours of flight time under IFR, of which at least 400 hours shall be in aeroplanes; and
(2) in the case of applicants of an IRI(A) for multi-engine aeroplanes, meet the requirements of paragraph FCL.915.CRI(a);