I wouldn't say that's particularly good value. My DH bought a ski outfit starter set on Mountain Warehouse for £80. That was salopettes, a jacket, and gloves.
You can pick second hand ski gear up from about a tenner an item on Vinted. Ski jackets are useful in this country, too. I get plenty of use out of mine through the winter as it's warm and waterproof.
My merino base layers were about £15 each (top and bottoms bought separately). I bought teen sizes on Amazon because I'm short. But Aldi and Lidl all do ski stuff, including base layers. I have some fleece lined leggings from Primark that work just as well as my more expensive base layers.
Mittens hold more heat than gloves, but if she prefers her fingers separate (I do), then you can get silk liners to put on first to insulate her hands.
I'd be concerned that the things you hire won't be good enough quality for her Raynauds, so I'd suggest Vinted for as much as possible and spend your money on decent gloves, liners, and socks. Don't forget gloves for when she's off the slopes, if they're outside in the evening. She won't want her ski gloves for that. I have Heat Holders from Amazon, and they're fantastic.