I have in the past just rang around the ferry companies the week I was travelling & asked for the cheapest crossing, never tried just turning up but I would guess they are likely to charge you more, if you call you can try to haggle a bit with them especially if you can be flexible on times & dates. Just booked with Eurotunnel + Tesco vouchers, paid a bit more than I should have as I was going to book last week, cost £55 in Tesco vouchers +£3 cash for a return. Noticed that you can use Tesco vouchers with the DFDS Dover to Calais/Dunkirk BUT only with a car up to 1.85mtrs :sad:. Could have got that for £49 each way so with Tesco vouchers it would have been £32 in vouchers + £2 . I had to call Tesco & the girl I spoke to thought they were intending to have more ferry deals that you can use vouchers for.
When I booked with Eurotunnel I gave my reg. & was told my van was a CI Rivera 18 JTD maxi :rolleyes2: it is a Rapido A class, she said the info was from there computer linked to the DVLA. I rang the DVLA & the guy I spoke to said all the info they had said it was a 3 litre Fiat.