I followed someones advice on this site last year and got family insurance with insure and go. This included winter sports and was for a years holiday insurance, just extended cover and it cost £60. Hope this helps.
I got a years insurance fom RAC for just over £100 that includes 20 days winter sport for anywhere in the world if your thinking of going away again within the year possibly the best cheapest way of doing it, only thing is the winter sport dosnt cover off piste sking so depends on what your after doing
Argos Travel insurance - annual multi trip for family of 3 £90 and you can spead the cost over 12 months at no extra charge. But its not just the cost you need to check out the policy - Argos is excellent and I have renewed with them.