I used Ally Bally Bee and TRoT (from Tri-talk) to arrange my trip. Seriously, then we used the top 30 must see list in the Rough Guide, identified the things from that we wanted to see, got a few ideas from the people above and then just winged it as we went. The campervan meant we had total freedom to go where we wanted, and using the TomTom satnav which has all the campsites in it with their phone numbers and a free 'Jason's campsite guide' then we jsut booked the sites on a lunchtime as we toured around. Worked really well as we spent a bit more time in some places than we thought we would, and a bit less in others.
Flights get released around April-May I think, and it pays to book early if you can. Don't believe the April race entry date as that drifted back ages. 100% definately talk to Roger at Gateway Campers as they worked out a lot cheaper than the big names that pop up on a google search, mainly as you don't get stung by all the extras that the other companies add in.
And Andy, do I still need to play admin on your posts? Link to Andy's Report 