Being one of those people who drives every day down the A30 through Cornwall, I will say every time, go for a campervan. By the end of the summer I could probably pick up from the side of the road where a caravan has gone over, virtually any part you might need! When we chose between a camper and a caravan we went for a camper every time. OK ours is modern and big but we started off with a small one. If you are on a site all you have to do is leave your number plate on a piece of wood stuck in the ground and no one should take your place. If you are on a hook up you will have to unplug but that takes just as long as it takes to take a plug out of the socket. It really depends what you want to use your van for. We tend to use ours for festivals and consequently arrive, put the handbrake on and put the kettle on! We don't use it to tour about during the day. Have a look at a magazine like MMM where you will find lists of cheap campers at the back and also advetisements for reputable dealers who sell cheap vans. They do exist ~ when we traded ours in the dealer sent it on to one of those. Have fun with your van.
Kathy