Which parts do you have in an 'emergency box' in your van? Accelerator cable Break cable clutch cable cork rocker cover gasket
Take a look here - http://www.gingersvw.co.uk/roadside-spareslist.html and the Tool Kit here - http://www.gingersvw.co.uk/roadside-toolkit.html
Fan belt. Nuts for the exhaust. A litre of oil. And a lot of bits like wire, crimp connectors, bulbs, fuses.