What to do if its snowy/icy on exam day?

You don't say what day the exam is on, but if it's later in the week there's a chance that the road conditions will be much better. Otherwise, you could try to stay the night before the exam at the house of a friend who lives within walking distance of the college - it's usually easier to travel in the middle of the day when roads have been gritted and the temperature is at its highest. Good luck!