You won’t need an insulated jacket. Presumably you are a noob. Falling over and getting up and all the walking and scooting is hot work.
You must have some base layers already from riding.
Mitts last longer than gloves and are warmer. You are unlikely to need the extra warmth in Europe.
Good trousers are a great investment, you will spend a lot of time on your ass.
Don’t forget goggles. Pricey ones have an anti fog coating on the inside. You don’t want to be rubbing at it. Goggles on and off all the time is a classic mistake you will get snow inside and then wreck your lens rubbing at it when it is wet.
Get yourself down to tkmaxx and find some cheap gear. It isn’t the best time of year to buy cheap snowboarding gear.
If you are going to pay rrp (as in the above link) you would be better off finding your local shop and going in and looking/talking/trying things on. You will get a deal if you buy a whole load of kit.