Brian,
Shame the event isn't in Hertfordshire, no danger of them bothering to salt the roads even when heavy snow is forecast!
Two weeks ago, when we had an incredible 2-3 inches of snow, it took me 5 hours to get from Stevenage to Welwyn Garden (about 7 miles) and Sue took 2 hours to cross Welwyn Garden a distance of hardly 1 mile!
Personally I'm not risking the salt.