Hi otherclive, you could try Springhill farm. It is about one mile outside Seahouses. http://www.springhill-farm.co.uk/
Thats thier site address if you need it. We have been a couple times and find it a nice quiet site which does allow dogs. With it being basically in the countryside there are a few nice walks if the weather is good. It takes about 15 minutes gentle stroll to the first pub in the town from the site.
Some nice views if you get a pitch at the front of the site and apart from showers there is a bath in the family bathroom. A couple washing machines and a microwave if you need it. The reception does hold a few of the foos essentials. The site is on a working farm so this time of the year you should get a good view of the new lambs.