Me and a friend are cycling from Brighton, England to Bordeaux, France and I was enquiring whether or not there was a cheaper way to cross the channel in central or western England other than Brittany Ferries (as we don't want to go to Dover!!!) with our bikes? Planning for in one month's time and the boat costs about £100+!
This looks like a cheaper alternative. Maybe they can consider your bicycle as a motorbike, or you can just ask a truck driver on spot to take you along?
I'm kinda a sensative to doing this wrong as I'm a newbie and I'm not promoting but there is loads of info at http://www.mybikeguide.co.uk/Bordeaux_Travel.php I hope this is still of some help.
Not sure how long you're going for, but the boat from Newhaven to Dieppe is a bit cheaper - and much handier for Brighton. £60 for a 5-day return or £80 for a longer one.
[ Edit: Edited on 26-Aug-2011, at 06:27 by bilboburgler ]