That's a more expensive option I would say unless you have held an FAA IR or other that has lapsed by less than seven years. To renew an IR lapsed by more than seven years in the UK requires completion of the IR(A) exam series: Air Law, Aircraft General Knowledge - Instrumentation, Flight Planning and Monitoring, HPL, Met, Radio Nav and IFR Comms. HPL and Met are credited to candidates who have previously held a CPL or completed CPL Theoretical Knowledge Exams. The Learning Objectives for the IR series exams are narrower than required for ATPL and much of it will look familiar (even after a number of years). A set of notes and access to good practice papers is essential and I would also recommend BGS (no affiliation). Following the theory, for the practical renewal, an assessment by the HoT of an ATO is required from where a training programme based on the outcome of the assessment, period the rating has lapsed by and overall experience can be proposed (EASA states the entire course must be retaken however the CAA has filed a derogation (see CAP804 FCL.615 IR(A) Theoretical Knowledge Examinations and Flight Instruction)).
Test must be completed with a CAA Appointed Approved IRE (same as for an initial and similar to the old CAAFU staff examiners in essence). Completion of successful test and application (assume you held a JAR-FCL licence so probably SRG1104 would be the appropriate form) will result in a Part-FCL (and National one if you wish) CPL/IR. Any other ratings you held will be recorded on the reverse page of the licence and can be added to the active page when renewed (again, for a fee). MCC however is non-expiring so should be included on the front page with the IR. I'm assuming you did not reach the experience requirements for an ATPL(A) issue and therefore if you seek employment I believe you would ultimately need to take the ATPL subjects again unfortunately (which of course may be the sensible course of action to start with) but there may be jobs out there where a CPL/IR would suffice perhaps? Not sure an airline would look at you though without ATPL credits. All factual guidance above courtesy of CAA Licensing Standards.
Good Luck!