We have gone via the boat to Spain and paid about £850 - dog cabins always fill up quickly and I dont really want to put our dog in the kennels on board. It was a rough crossing but quite enjoyable. We have also gone via the tunnel which is so easy and not too badly priced. However this summer we are going to try the Newhaven-Dieppe ferry, really good prices (better than tunnel!) and drops you a bit further south and avoids the congestion around Paris etc.. looks ideal to me!