Ouch! Firstly, I hope you're ok.
Is your GTI bumper conversion all declared to your insurance company? I don't want to alarm you, but if it's anything out of spec they (the van's insurer) will declare yours void and refuse to pay.
Might be worth taking some cash, which IMO is often the best case for sub £1k claims - by the time hire cars, bodyshop's quadrulple rates and everyone else having a cut has been added up, it costs an arm and a leg... it doesn't come out of some magical pot of money, it gets lumped onto everyone else's policy, including yours for next year.
You also have to consider yours will possibly be listed on HPI and come resale it'll affect its residual value, so you could come out worse off in the long run by claiming.
Mike.