Put a bag of grit/salt mix and a proper steel shovel (not one of those stupid plastic things that break) in the boot. Several rubble bags too for grit, the wet/salty/rusty shovel, snowy boots. An old towel isn't a bad idea either.
Choose routes that avoid (steep) hills as much as possible and that keep your options open. Although the Highways Agency gives priority to motorways - stay off them, it's too easy to get trapped.
I'd add to the official advice on warm clothing etc. that a 'fleece' blanket has the best warmth-for-weight and stays dry as it's water repellent.
Tyres will make the most of the available grip if they aren't allowed to slip at all - the basis on which ABS works. Spinning the driven wheels just fills the treads with snow, turning them into slicks and polishing the 'road' surface.
Drive with the utmost smoothness and delicacy to give the wheels the best chance of keeping their grip. Stay in as high a gear as possible - where you can, start in 2nd and slip the clutch. Use minimal throttle. Hang back and anticipate so that you avoid coming to a stop. Plan not to use the brakes - they won't have much effect and ABS doesn't work properly in very slippery conditions.
If you get stuck, spinning the wheels (in frustration) only makes matters worse. Get out and put something (grit, sand, twigs) under the wheels to give some grip.
I can afford to be smug at the moment; so far we've only had a slight dusting of snow