Oh dear, this is making me so homesick! We do want to be out in the sticks, and in a lot of ways would love the colder weather. Our border collie would too. We had a place in the Scottish highlands for a few years and managed ok in the winter, even when snowed in. (apart from the short days.)
I realise though that we'll have to sell our place here first, and that won't be easy.
Anyway thanks for all the suggestions, and I'll be following them up.
I had a few holidays in Bamburgh as a child, with a cousin's family, and would prefer the coast, but already know it's outside our budget.