In chat, falstro mentioned the "UK IMC rating" and described it as "a lighter version of an instrument rating, allows enroute IFR, but no approaches or departures" (although to be fair he also said that he isn't familiar with the exact definition).
The name "IMC rating" implies that it allows flight in IMC, not just filing IFR in VMC for procedural reasons. But if so, and if approaches are not included, then it seems like it would allow a pilot to fly into IMC with no safe way out again if an emergency required an instrument approach.
So what exactly is a UK IMC rating, what does it not allow that a full instrument rating does, and what is the advantage of having it?