Back in July for our anniversary, Nick and I went on a trip to Sissinghurst Castle in Kent. It's a beautiful place to visit, with it's stunning gardens and the amazing view you get of the Kentish countryside at the top of the Tower in the castle! Although tickets are pricey it is National Trust so it's well worth the entry fee. We were half tempted to get the yearly National Trust pass but there's not actually a lot of places to visit near us - but it is a good bargain if you are under 25.
Make sure you check out the castle itself, although a lot of it isn't accessible to the public (or at least wasn't whilst we were there) and take a walk around the lake - it was such a warm day so it was nice to be under the shade of trees! There is also a little cafe near the carpark so you can pick up a nice refreshing drink after all of the walking! Sissinghurst Castle is one of those places where you can visit all year round, I've visited in October a couple of years back when it was just as nice but a little less busy!