Assuming you have an EASA Licence then a Single Pilot Multi Engine IR is also valid as a Single Pilot Single Engine IR.
Look in the Ratings Section of your Licence, it should read:
"IR-SP-ME class/SE" (where SE = Single Engine)
Just in case you had not considered it, irrespective of whether VFR or IFR, you will also need a valid Aircraft Rating which, from what you have written, I would believe to mean a valid SEP Class Rating.