A lot depends on what the pilot wants out of this.
If he/she wants to fly UK IFR for real then not only does this tend to imply aircraft ownership or part-ownership (because one cannot generally rent planes suitable or even legal for IFR) but also getting a real instructor who knows IFR. These are scarce on the PPL scene.
If he/she wants to get a Rating which enables him to enter cloud en route, on a very occassional basis (this seems a common reason why people do the IMCR) then one can do it much more easily. Personally I think this is not a useful approach however because being able to fly an instrument approach is the ultimate lifesaver, and this implies that the IMCR holder should be able to fly every approach plate.