Hi Jay - welcome to PPRuNe!
You get no time off the IR if you've done an IMC. Sorry. Of course that doesn't mean that you shouldn't do it, or that it won't be useful - but you'll still have to do the full IR course.
One alternative is to do an American, FAA, IR. You do get time off that course for the IMC training (or any other instrument flying) that you've done. Mad, isn't it, but that's the way it is. Once you've completed your FAA IR, you'll then need to convert it to a JAR IR, which is a minimum of 15 hours, so all in all it's probably still not worth it from a saving-hours point of view.
Hope that helps.
FFF
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