Please see below.
I was just sent this by a friend who told me that she can vouche for this service.
From what I understand you enter for free tickets to Friday or Sunday and if you win you then upgrade for a full weekend ticket for 50 quid. Not sure if that includes camping.
I've already purchased weekend/camping tickets at the full price so I won't be trying for these but they might work for you if you're still on the fence.
All the best,
"We're now pleased to announce our massive Hop Farm Music Festival free ticket giveaway! We have bought 500 day tickets for the Friday and Sunday of the festival and we're giving you the chance to get your hands on them for free - apart from the small admin fee to cover our costs (and by small we mean £5.40 smallprint fans...).
To make it fair for everyone the tickets will be made available in two batches; the first goes live from 6pm tomorrow (Wednesday June 13th), and the second batch will be released on Friday June 15th at 1pm.
CLICK THE LINKS BELOW WHERE YOU CAN GET UP TO 4 TICKETS FOR YOU AND YOUR FRIENDS
Free Friday: http://www.supajam.com/get/tickets/hopfarm2012-friday
Free Sunday: http://www.supajam.com/get/tickets/hopfarm2012-sunday
That's not all though... We've also negotiated a special upgrade option; those of you who want to enjoy all 3 days of the festival can upgrade your FREE day ticket to a full weekend pass for just £50!"http://www.supajam.com/get/tickets/hopfarm2012-friday