I'm going up snowdon in February?

vI'm going to snowdon in about 15days but I'm still not sure what to wear.

I'm especially concerned about the kind of coat I should be taking, should it be like a ski jacket or just a good water proof and wind proof coat?

(Links to the type of coat I need is appreciated)

What should I wear under that?

I know about hiking boots and trousers already, it's just the top half,