They are plastic cleats and the reason I thought I needed covers is that someone said they wear out really easily if you walk on them? I could take a picture of them tonight if that helps - they are shimano pedals and DHB shoes.
So the best thing will be a couple of pairs of thin socks, then my shoes, then some old thick ones with a hole cut out for the cleat and then the wind proof overshoes which they currently have in Aldi 
Thanks everyone, hopefully this will keep my toes toasty warm and stop me becoming a right grumpy bugger on the ride! 