Marathon training: this is not a good weekend for snow

We have a good few inches of snow at the moment, and it's so cold there's no chance of a thaw anytime soon. I'm extremely gutted as it's such a key weekend for marathon training, being the penultimate long run before the taper begins. I was all set for getting up early and heading straight out, being home by 10am. But I'm just not prepared physically, mentally and practically (my trainers wouldn't cope) to run in the snow, in sub-zero degree temps with the windchill; I'd lose my running form and risk injury, especially over a long run. Instead I'm planning a treadmill run tomorrow, but I just can't see myself running the full length of time I'm supposed to without packing it in out of utter boredom, I hate that the only think to watch is the little computer screen that tediously makes every minute pass at snail pace, so we will see how I get on... Come on snow... Be gone!