Bagwell Farm, Weymouth is open all year.
It has new hard standings for R.V`s & Motorhomes, right by the toilet block.
Gets busy xmas time and I am not sure if they open the restaurant for xmas, but it is closed normally out of high season.
But a frequent bus runs from the site into Weymouth Town centre. (Approx 3 miles away).
The site is set in a valley with beautiful views across chesil beach and the fleet lagoon.
Being where it is it is fairly sheltered from most prevailing winds, which you get a lot of on this coast in the winter. (And any time come to think of it
)