Winter Touring

Well I hate to admit that we are a fine weather caravanners! we usually only use our van March-Oct. So having wintered off my van and put her to bed for the winter...., my husband has decided we should have a "Twixmas" break for a change.

So I am wondering if there is any advice from seasoned winter tourers about what I need to do (water, gas etc)  to ensure a problem free week in what could be freezing conditions?

Many thanks