Guy, you'll need the circulation pump retrofitted, but I'm sure you have done that anyway right?
Evans waterless coolant is rated down to -40 degrees so should be fine (I'm sure other alternatives exist too)
Just make sure the windscreen concentrate is rated low enough (some are -15 degrees which is not enough), for example this one
http://www.eurocarparts.com/ecp/p/ca...7312&0&cc5_701 You won't need to use it in such temperatures, but you don't want the reservoir and hoses to freeze and split
Also make sure your battery is in good nick, as an old battery may work fine in warm temperatures but not when it's -30 degrees
