nope, ive lived here for 36 years. much of our greenland had been developed on. i only know of organised projects like the Ashton Court Festival. never thought of camping in Bristol really...sorry
The following are all Areas of outstanding natural beauty:
The Cotswold hills (North East)
The Mendip hills (South)
The Quantock Hills (near Minehead)
The Wye Valley (on Wales/England border)
The Exmoor and Brecon Beacons national parks.
All are within an hour drive from Bristol, although Cotswolds and Mendips are much closer.