Thanks for all of the replies, unfortunately my license is firmly EASA so I wouldn't be eligible as I understand it to have an IR(R) put on to my license. I'm actually considering just getting the SPA IR and saving a lot of fuss, also opens up my options going in to Europe.
I'm with Fireflybob though, I've spoken to the CAA a lot in the last 12 months and it seems as though regulations are being tweaked virtually all the time. The fact is i'm qualified to shoot a CAT 2 in the day job, yet not qualified to fly in to some cloud in a Cessna on the weekend.
I appreciate the replies though and glad I asked!