There is no black and white. If you have an IMCr and you are flying to France, you must ensure you maintain VFR in French airspace. Simple really.
The grey area comes when you have someone with a foreign IR who is very capable at flying IFR, but not allowed to due to their tail letter. Again this is more of a muddy black area as we know that the flight should be, as with a), be planned and executed as VFR, but because they would be rated if a letter was changed, then it is *more* excuseable (but not in the eyes of the law I suspect). Certainly not an emergency though.
However what with the weather forecasts being so !!!!e, I have planned and flown a VFR flight to be confronted by either scud running at 1000 agl for 200 miles, or climb a few thou through to safety on top. Turning back would have meant a whole load of hassle.
I do confess to shooting an ILS in France with the wrong tail letter once upon a time many years ago. It was either that or cross the channel at 400' which another G reg aeroplane, (with JAA instrument rated pilot onboard), did just behind us. Madness if you ask me, their reason for not climbing into the cloud was they "didn't know the procedure". I just asked the controller if I could have the ILS as I was now IFR and he said okdokey.