There are zillions of blokes who are going to have to change their vans including a fair few who won't realise and get nicked - £2000 fine.
At least you have sussed it before the event . Get a Polish registered van seems to be best option, no congestion charge, no LEZ. no tax, no MOT no insurance, no parking tickets, no speed cameras, no bus lane cameras, no box junction cameras, no traffic light cameras.