We were there recently (Easter school holidays for two weeks) and many of the roads to crags were closed - however when we queried if we could have the key from the guard (cheeky I know) he said that we couldn't drive to the crags "danger of unexploded etc...." but they were happy for us to park at the gate and walk in. I got the impression it was a way of closing the areas without fuss - they figure we're all too lazy to walk in and so they won't have to monitor comings and goings etc, but if someone gets cranky about it they say "They're not closed, you can walk in" - anyway the long and short of all that is that you can still get in if you're prepared to walk.