Nowton Country Park is a great and free place to take the children that is open all year round.
It has a children's play area, maze and a few different walks that you can take over the 200 acre property. Dogs can be taken there but must on a lead.
It just shows you there is plenty to do without having to take the children to a theme park, all you need to do is pack a picnic and load them in the car!
That is what I love about the English, they appreciate their parks and spend time with their children. So get out there!