Hi Mark,
I've avoided the Klein Strand site in the summer because of the very busy water park - but I doubt if you'll be using the water slide or jet-ski in January?, and it's certainly better than the other alternative near the city of Brugge (Camping Memling)
However, Camping Blaarmeersen on the outskirts of Gent (about 30 minutes further along the E40) is probably the best camp site in Belgium - and certainly the best in the Northern part of Belgium. But Klein Strand is probably a good second.
Both have a good to very good restaurant - which offer a reduced menu in the winter - but you can do a whole lot better in the surrounding towns and cities (particularly Damme to the north of Brugge)
If you search this forum for some of the questions by Barney (Cumbria), or Camping Blaarmeersen, Camping Memling or Camping Klein Strand you should retrieve a load of useful information.
Regards, Robert