Departing knowing your destination will involve an IMC descent is asking for trouble. Such an IMC descent is pretty much guaranted if the forecast is overcast x with no prob relief.
However anything involving a probable VMC on top that becomes less than VMC is going to be tough to argue the toss over should you decide to press on.
Anything involving an arrival with a reasonable prob of broken or scattered is a reasonable departure.
The get out of jail card is to declare an emergency; I cant imagine if you have departed in any of the above circumstances (except the first) a prosecution would be sucessful.
The rating has had no idea whether you are in France or the UK anymore than the fella with an FAA IR is more or less capable of flying an approach in IMC in France in a G reg aircraft (which would of course be illegal). I would love to see a case where this happens and the pilot is brave enough to fight his corner in court.
So let me see, the FAA consider I am qualified to fly the approach, the JAA consider I am qualified to fly the approach if the aircraft has an N on the side, but if I paint a G on the side, all of a sudden I am not long capable. That is a convincing argument - not! Imagine try to persuade a jury they should convict the pilot. I bet the judge would have to do a lot of directing.
