Don't forget you can do it online too. That's great for when you've lost most of the documents. All you need is for the car to be listed as insured and MOTed on the database and then it will let you click through. You need the document reference number from the V5 though.
i was just checking as looking at getting a car and the owner had said they would renew for end of month, so i don't want to be stuck in the middle etc.