As Stan says you must either have the FI Restriction removed or meet the full stand alone IRI entry criteria of 800 hours in accordance with IFR etc.
The course to remove the no applied IF restriction is 5 hours flying and 35 hours ground training. You then take a test with a FIE and apply to have the restriction removed.
Provided you have a UK CPL you will then be able to teach for the IMC rating. If you hold a JAA licence you will require either a valid IMC or IR as well.