As has been dicussed previously, according to the EASA Aircrew Regulation (Regulation (EU) No. 1178/2011) JAR-FCL licences became Part-FCL licences on 8 April 2012, and in accordance with Part-FCL the holder of such a licence requires an Instrument Rating (IR) to act as pilot in command on an IFR flight.
So you can't fly under IFR without an IR unless perhaps if you have an old UK PPL or you have some sort of instrument rating (IMC / IR).
Last edited by riverrock83; 29th May 2012 at 15:28.