Worth keeping an eye out with this airline as there is a possibility they may decide to do a year round schedule in the future from Gatwick.
Currently it's Oct - April but their load capacities have been very impressive since launching the route and revenues are up overall. However it's a complicated situation as Norse currently lease six of their 787 Dreamliners to Indigo Airlines which were grounded due to the Iran conflict but are apparently now being introduced back into service.
Bottom line is any of these budget airlines could go out of business at any moment so be aware when booking tickets well in advance.