Depends where you are, what you want to do, how far you are going but BCR's rates for a Luton are £70 per day or £300 for a week - extras are overseas breakdown insurance (can't remember what we paid) and you pay for mileage above 200 per day.
First time we hired from them (when signing for our first French house) we got a Luton at no extra charge because the standard model was not available. At Portsmouth P&O (then running to Cherbourg) refused to take it because it was higher than the van we had booked. But Brittany Ferries took us to Caen with no trouble. So we got our house, even though turning up at the notaire's in a 'rent a wreck' clutching a bank draft for many thousands of francs caused some amusement. Neither notaire nor sellers spoke English but they understood that slogan. The van was invaluable for the next couple of days buying furniture, gardening equipment etc. So a couple of years later we hired from them again, a bigger Luton, for the final move to carry all the stuff we hadn't been able to fit into our own standard transit.
And I have preferred Brittany Ferries to P&O ever since. With good reason, as things turned out.
Edit - there's a follow-on story which I might tell you some time (unless you agree to pay me) involving a bed, and how we found the other hire company I mentioned that would allow you to go to France.
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