In reply to Flatus Vetus:
We get pretty busy with school groups this time of year, but not every day is busy - especially if the weather is nicer outside. If you are needing instruction then it is definitely worth booking in advance. If you are already an ice climber and want to book a slot in the ice wall to climb yourself then you can sometimes get away with just showing up/ giving us a bell on the day to check. There are some days where it isn't possible to do this and more notice is needed, so it just depends how much flexibility you have really.