What sort of heating do you have? We've found that caravans warm up really quickly with the gas fire and the blown air system is good for keeping them warm. I'm hoping we can get away for some weekends in the new van as its better equipped.
We are off to Chatsworth at Easter in our new van, which we collect in mid March. I need to bring the old van over to the house to empty out completely and check over before we part exchange it so might sleep in there on the drive for a night before it goes! If you have good heating I think you can go caravan ing all year, though we haven't ever been away in the winter.
We've booked the Easter weekend as a definite, but if it starts warming up a bit in March we might do a weekend somewhere close to home to give the caravan an airing and sort out any bits and pieces that might need fixing.