with permission i have no idea sorry, however without permission there are many a place you could find yourself just take a look on google maps for any decent size woodland and take a look see. This is something i am going to be doing i have found a good location with signs of previous campers a long time ago. I am going through a separation at the moment so now is not such a good time plus i still haven't got all the kit i need for a night out. I should be sorted in a month or so but then it depends on the weather.
good luck