There should be a claim form to down load on your local council website. Hampshire have one or at least they used to have one a few years ago. I hit a lump of lime stone on the M27 while riding my RS250 and wrecked the front wheel. The stone had rolled into the road from work they where doing on the hard shoulder. I down loaded the form but in the end I did not followed it up as I got another wheel cheap, but if there is more at stake give it a shot.
Mike