Is Winter Pack worth the £355 ?
It's not the best value option on the list, but if you want heated seats then you have to make the call, nobody else can (or indeed should) decide for you! I went for it as I want to be kept warm in winter.
CraigW is kinda' right, but I disagree on some things like the camera and park assist that if specced, are cheap, effective options. Taking it further, the entire car is a luxury so I just look at options as part of the cost of the car and be done with it.