Hi I went to Durlston Country Park in Swanage for the first time today despite living in the area for many years. It was absolutely beautiful and I can't believe I've never been before.
The views across the Purbecks are fantastic, there is a castle with an exhibition, educational trails to follow, a lighthouse, huge globe and walks along the cliff top with lots of local wildlife. There is a very posh cafe but we took a picnic and there are plenty of picnic tables. Best of all, we only had to pay to park.
I don't know if it is too far away to add to the local listings, but if like me you haven't been before it's definitely worth adding to your summer holiday planner. The only thing I would add is that the cliff edge isn't walled off the whole way along, so if you have little ones don't let them go too far ahead.