TX Max also sell ski wear at cheap prices.
Jakets and trousers / salopettes are certainly thinner than they used to be ( my DH still has a lovely pair of purple salops with a purple / red/ navy jacket!)
Luckily he doesn't wear them on ski holidays now.
It is the filling that keeps you warm, so depends what is used. It can also vary on how waterproof ski clothes are.
We used to buy Trespass skiwear for our sons which was cheap but kept them warm and dry.
Skiing in January/ February can be very cold, March / April is usually sunnier and much warmer. If it is snowing/ cloudy with a wind blowing it can feel bl**dy freezing especially when you are exposed on the top of a mountain!
Definitely important to pack layers - we pack short sleeved thermal vest, long sleeved thermal vest, cotton polo neck ( some have a neck zip ) and also a ski fleece.
You need sunglasses suitable for snow/mountain and also goggles for cloudy/ snowy weather - yellow or orange coloured lenses are best.
Warm woolly hat, and ski gloves. Some ski gloves also have a pair of inner fleecy gloves for when it is very cold.
Ski socks. I wear a pair of tights under my trousers as well usually.
It is also worth having thermal leggings to wear under ski trousers if going in December - February and it is very cold.
Sun cream ( suitable for snow/ mountain ) and also lip salve for chapped lips.
If pockets in jacket are not big enough for goggles, hat, suncream, camera, water, snacks etc, then worth wearing a small backpack which secures at the waist so it doesn't move around.
Even if the sun is shining in the morning, the weather can change during the day, so you always need to carry goggles and warm hat.
The school should provide a list of things to take. Hope she has a super time!
Where are they going?