Hooves and I went for a dog walk in the woods on Buttersteep Hill in Ascot in February. It is a wonderfully wild and natural area that forms part of Swinley Forest, in Berkshire. It is perfect dog-walking territory: you are likely to see other dog walkers, the occasional runner, and if you are lucky you might see one of the Alaskan Malamute dog sled trials, which are held a couple of times a year in this section of the wood.
The area is large enough for a really good, long dog walk, and you can meander in down any number of the wide trails, creating a different circular route each time you visit.
There is no car park, but you can leave your car on Woodlands Ride, Ascot, close to the entrance gate. (map) There is a bin here for dog waste. (streetview)
There is not much to say about this area except it is perfect for dogs, perfect for walking, and perfect for clearing 
the mind…and we think it’s beautiful. It’s a real oasis.
I am told car parking charges are soon to be in force
Apologies for the delay replying. The last time I visited there were signs saying that parking wold be charged for soon, so I think you are right Gerri.