The more relevant requirement is Appendix 6 which states:
2. An applicant for a modular IR(A) course shall be the holder of a PPL(A) or a CPL(A). An applicant for the Procedural Instrument Flight Module, who does not hold a CPL(A), shall be holder of a Course Completion Certificate for the Basic Instrument Flight Module.
The requirement, therefore, is to
hold a CPL, not merely to have completed the training.