you will need your elementry food hygene certificate, this costs about £100 and is a one day course, you will need to have a traders license obviously, the van must have 3 sinks, it will need to be inspected by eho but you will find out more about this when you apply for your license,if you are going to be preparing stuff in your home kitchen(ie chopping onions,buttering rolls etc) that will need to be inspected too, you will need to keep daily temperature checks on your fridge and hot holding food in the bain marie, then there is doing the books, as part of the conditions of your license your books must be up to date and be ready for inspection at any time, also there is the whole inland revenue bit that i aint too clued up on anythin else?