On the couple of occasions we've had long-lasting snow and ice, the problem has only been the side roads at the start and end of the journey. The main roads are clear within a day, but I've still not been able to get the bike out because of the 200m of ungritted road between me and them. Assuming they are reasonably easy to put on and take off, I'm thinking that snow-claws might be a way to get over that.