I think its fair to say that if you have to file an IFR flight plan you must have an IR. Certainly under the new EASA rules you will not be able to fly anywhere in Europe on an IFR flight plan without being the holder of a valid IR. So you will not be able to fly back from France or Belgium at night.
On a recent Clarkson program, he raced James May, who was flying a Cesna back to the UK from somewhere around the Mediteranean. James May had to land as night approached because was not qualified to continue at night, he obviously didn't have an IR.
would I still just be able to file an IFR flightplan but maintain VMC like in the UK?
If you don't have an IR or IMC you have no choice. Remember ATC don't know you limitations in such cases, so it might be as well to include your limitations in item 19. Clear of cloud, in sight of the surface. Until Part FCL comes into force it is still legal for holders of a UK licence to fly IFR without an instrument qualification so long as you obey the limitations of your licence, but EASA will put an end to that.