If, as it seems you are going to Spain for the winter, have a think about the west coast of France route. Either from the western channel ports or from Dover, look at Poitiers to St jean de Luz to Zaragoza to Valencia to whereever on the Med. Coast. This has the advantage of missing the potentially cold and icy middle of France and traffic problems or worse round Barcelona. Caravan Club Europe 1 book will show you the open all year sites along this route - we have used it for the past 5 years without any problems and with very little traffic on the main roads.
Once at Valencia, you can go north up the coast or south down the coast. Early in the year, going south is the best bet, with the alleged sunniest place in Europe just inland from Almeria.
Hope this helps - can't write more at the moment as off down this route ourselves. merry christmas and happy touring.
