i really enjoyed Hyde park but as far as no cars go isnt gonna happen in london. but hyde park is a great local for getting someplace in decent time. i was able to go from The Hard Rock Cafe to Buckingham Palace in about 30 minutes walking but i was also going to all the stores and such. if you are really looking for some chill time head out to Stonehenge its about a 30 minutes drive from Portsmith nice open country and a great place to go and see the seanery.