Aye Up,
Scarfell, you beat me to it!
Many years ago whilst training for the JSMEL winter (SMLTB) I was fortunate enough to be able to spend some time with RAF meteorologists.
They said practically the same as you - quote, "If anyone tells you that they can accurately predict UK weather more than 48 hours ahead - laugh!" In fact during the training and courses in both Scotland and Norway it was nearer to 24 hours. As you state there are so many variables a prediction can be wrong before its even broadcast.
(Apart from during large, slow moving systems or stable high pressure perhaps). Does make you wonder about all that computer and radar malarchy! I tend to view the long range weather forecasts in the UK a bit like astrology. Still, the weather presenters are easy on the eye!
Incidentally TonyUK - I was always taught (and went on to experience often) that weather-wise the wet cold of the Scottish highlands could be far more dangerous than the dry cold of the Alps and Scandinavia -so I now where you are coming from.
Bring the cold and snow on - let's have a real winter for a change.