Try and be taught the IMC rating by someone who is an experienced IR rated pilot. You will be wasting your time and money if the instructor does not have an IR, and you will most likely have to be un-taught bad habits.
If you are taught well, it should mean you pass the IR in minimum hrs, and that will save you money considering every extra IR hr will cost around 350 pounds!
Also consider that the IMC does not make you an IR pilot.