Do this trip in the winter! Such magical surroundings whilst the whole area is covered in snow. Don't worry if you have no previous experience of using crampons or ice axe - there is plenty of opportunity to get used to them and by the end of the trip it feels strange walking about without crampons!
The refuge is very basic and standards of hygiene are not great in the bathroom areas. This is fine as long as you are expecting it - read the reviews and the trip notes as they do mention this. Hot water is available at times but is very limited. Shower when you can!
Take chocolate - thanks to the rest of the group who all came really prepared with lots of great quality chocolate to share. This was really great each day when we stopped - especially at the summits.
Alcohol is really hard to come by in Marrakech and generally very expensive. A little research can find places to get a drink but don't expect restaurants to have alcohol readily available - especially near the main square.
Take gaiters - although they are only optional on the trip notes - you will be walking in deep snow so invaluable.