As said you can buy a new one from Renault, around £80 mark, they give you a couple of forms to fill in, you then have to take car and forms to a police station and get them to confirm the vehicle is the correct one, then take it all to Renault dealer who check car over and they then send off for it.
You can buy blank vins off eBay or kit car websites and get it stamped up or ingraved which is cheaper and easier but also as mentioned may pose a problem when you come to sell