We've got season tickets for this our local festival so we'll be there. There is a caravan/?camping space at the Ashcroft Centre just round the corner from the main venue. Many people come down and staythere because although it is outdoors it is quite a cosy gathering. I am more into my creature comforts though! The local tourist board

http://www.resort-guide.co.uk/intro-pages/destinations/fareham.htm

may be able to help you but it could be too short notice for anything close. Sorry can't be more help - maybe see you there if you get somewhere.