Apologies if this has been posted before, but several of us at School are driving the kids on Friday, and a few questions were asked about seat belt legalities. I found this, and there are a few pertinent sections if you have a camper van, certainly at around questions 15/16 if I remember correctly. May be of use to someone.
http://www.dft.gov.uk/think/focusareas/children/childincar?page=FAQ&whoareyou_id=" onclick="window.open(this.href);return false;
http://www.dft.gov.uk/think/focusareas/children/childincar?page=FAQ&whoareyou_id=" onclick="window.open(this.href);return false;