I've managed to get 2 tickets today, they released returned tickets from sponsors.
You get entry a day earlier (Thursday!) so you can set up camp early and have a look around before the crowds arrive on Friday, the on-site trails are open (if you've got a trial access ticket) all the motorcycle manufacturers are bringing their entire test bike fleets a day early, so are running test rides on Thursday, great if you're after a new bike or just fancy giving them all a try and a Thursday night party concert with some pretty good acts on! Looking forward to it