We stayed at the Stonehenge camp-site http://www.stonehengecampsite.co.uk/facilities about 3 years ago, facilities fairly basic, but clean, tidy site. Nice pubs short walk either way, about half a mile if I remember correctly, friendly owner. Don't know if its been developed any further since we were there.
If you are planning to visit Stonehenge itself you have to pre-book to be sure of getting in. Around £15 per person if you are not members of English Heritage. Or just drive past on the A303!