From experience, as similar happened to me on a DC, get out of van ask if other driver passengers are ok, swop details etc, examine damage, and drive home, ring insurance next day when you get up with stiff neck and back.
Insurance then arrange for replacemt Daewoo matiz or other small car, to be delivered not a van, you argue you need a van for work, eventually they provide a new van, go to hire co to sign your life away and be told by some kid about damage waivers, dirty vans etc will all be chargeable etc, go out to inspect new van and despite whats just been told you, its full of tree branches and general rubbish.
You then go to GP, who diagnoses Whiplash and back pain and refers you to a physio to start in a few weeks time.
A few days latter your van is taken away and repairs undertaken about 4 weeks, and you get your old van back.