Amanda, you have the very best Winter tyres for your Monza Shadows.
As GolfTi says, much less trouble swapping tyres over.
I am still in two minds. We don't suffer from your terrible conditions. (North Yorkshire is the worst hit, I hear).
Now that all the roads I use are very well salted/gritted, I find the journeys quite easy. In fact, there are hardly any cars on the road and my journey to work which normally takes 40 mins, was accomplished, each way, in less than 20 mins!
If I do buy, they will be Conti 830P 225/40 R18 V tyres. Like yours.

I just have to source them. They seem to be as rare as
hen's teeth.