You have Three choices either check/have installed a BBQ point on the exterior of the van and plug the Cadac into that with the appropriate connector and a length of extension hose OR
Take a cylinder out of the locker and attach to the Cadac using a regulator/hose combination. OR
For limited use, buy a camping gaz 907 and use that, saves flaffing about with disconnections, its cheaper than an exterior point and gives a standby gas bottle exchangeable world wide whereas your Calor cylinders are only viable in the U.K