If I remember rightly, I think there is also one in Halifax that uses snowflex. In terms of discounts these things are expensive to run but often they do offers on arrival in off season and normally have peak and off peak hours. So if you are lucky enough to be able to duck off work early some days that would be a benefit.
In terms of what to expect the man made snow is a little slow and becomes icy quite quickly with a lot of traffic in a small space. So if you can go in the morning you are generally better off.
You will find a lot of beginners there just trying to get their basics down which is great but doesn't make for great riding if you have some experience. So best shout is to go off peak hours and use for working on tricks etc.
Hope this helps, if you look at the "Having a blast" thread Dave is doing a good job of documenting his indoor experiences there