They do provide you with a thermal suit and boots.
The brand is actually irrelevant. Brands, like anything, are all about cost and look.
There are two important things to remember when packing for the cold.
1) Cotton kills = any clothing that is cotton, underwear, t-shirt, jeans, hat, etc. once wet will not dry and make you cold. Wool, fleece, etc. is what you want.
2) Layer. Google how to layer for winter. 2-3 layers. It’s typically, base layer, warm layer, and waterproof layer. (Again, depends on activity).
*Wool socks and good boots are a must.
Recommendations for brands (US)
-Arcteryx: Very $$$, but will last forever. Buy their stuff if you foresee yourself doing outdoor sports numerous times every year.
-Khul: $$ - my personal favorite.
-Patagonia/Northface: $$-$$$, always a safe bet.
-Any mass produced brand Eddie Bauer, LL bean, etc. may not be cheap, but it will get the job done for a one and done trip.