crazyscot

Wool is warm, and crucially it is warm when wet, and makes for excellent cold-weather gear. Linen is more sweat-wicking than cotton and is nicer next to the skin (damp, sweaty, things next to the skin can be nasty even under layers of warmth), cheap synthetic fabrics are VILE in this regard but the expensive sort sold to athletes and hikers are much better. Fur is good for outer garments, as are down jackets (although you are probably more likely to be able to buy synthetic fleece). Watch that cuffs (of sleeves and trousers) are tight (or overlapped by socks or gloves) so that the cold can't get in at the edges.

Any part of the skin left exposed will rapidly get cold, so socks, gloves, hats, scarves etc. are just as essential as jumpers. A face covering and goggles may be required outside but obviously can create problems when, eg, trying to eat.

You need (for health) to wash a good deal less than 21st century standards would suggest, washing small parts whilst keeping the rest covered may help. Another alternative would be to join a gym and wash in their showers (gym changing rooms are, IME, generally heated).