As I'm from Norway I have plenty of experience on all kinds of winter conditions (ice, snow, slushy tarmac). Go with expensive ones, like Nokian or Continental. They're worth the extra £'s and will last you longer. It's surprising how cheap winter tyres' performance will degrade over a relatively short amount of time. Unless the snowy season is less than a month and the sunny season is rather cold you should under no condition use the so called "all season tyres". The rubber compound (?) will be equally bad for cold winters as for warm summers.