In reply to wiggi: Depends on the weather. it can get really hot on the glaciers in the sun but frighteningly cold when the weather gets bad but I'd assume if it was really bad you'd not be out in it. Sorry, I didn't answer your question but it's hard to say anything other than I'd rather take one and not need it than need one and not have it!
Well worth having, such a pleasure not to be cold! On the other hand avoid getting pissed when you're wearing it and falling onto a barbed wire fence as a mate of mine did staggering back from the pub in Glencoe
At least we could all see where he'd bin the next morning.
In reply to wiggi:
Unlikely to need a down jacket, the course provider will let you know. Assuming you will also be using the jacket in the UK I would consider a Primaloft 1 jacket instead. For example ME Fitzroy