Crossing by ferry

You had better be really good sailors to tackle the channel in winter...

Suggest you also look at Eurotunnel as a dry land option.

So , Peter , this means ferries don't work in winter time ?

They can be subject to delays and cancellations, and the crossing can be uncomfortable.

It's "swings and roundabouts" driving to Spain from the UK. 

It depends how good a sailor you (all) are if you're going to cross the channel to the Caen area. That can be quite rough. 

The crossing to Santander/Bilbao has the potential to be even rougher - the Bay of Biscay is not noted for its calm seas. 

The channel rail shuttle avoids the possibility of turning green on the  high seas, but then you're faced with a long drive that, even going flat out, will take at least 2 full days, and could easily spill into a third day if anything unforseen were to happen. 

One thing to be aware of with the  "Chunnel" is that if you're also planning to drive back using the same route, but you haven't booked a "return" journey, you are quite likely to get pulled out for a spot search on the way back - basically, they don't like anyone just turning up on the day, and booking a one-way ticket, even though you might genuinely not have known when you were coming back on the way over - makes them think you're hiding  something. It's also a lot more  expensive! In addition, using the Chunnel means you have to cross the River Seine. That means either going around Paris, which can have various degrees of difficulty depending on what time of the day/week you travel; or going via Rouen - where the motorways don't QUITE connect up into a continuous route (although, having  gone via Rouen a number of times, and got used to it, I personally prefer it). Don't forget to  factor in: fuel, overnight accommodation, and (mostly French) road toll costs. (Some stretches are free, some not)_.

If you can cope with the sea crossing, the Cherbourg peninsula is probably the best, and possibly the  cheapest, of those 3 options.

HTH

I use Brittany ferries 4 times a year but to Bilbao or Santander. In the last 8 years, only once been pulled for customs check which took less than 5 minutes with a stuffed full SUV. The check is more to observe you. They are very good at detecting someone who is not following rules. The crossings are normally OK but we once had to pull into Brest due to a hurricane. Brittany do these crossings very often and have both crew and ships that are very capable. They are not SAGA ;) Join the BF user groups for more info. 

I recommend Saga holiday cruise crossings across the bay of biscay...all your boxes are open by the time you arrive for customs 

Hi 

We recently came across on the p&o Dover to Calais, only an hour and a half , straight through in the van , free for pets to stay in the vehicle, and it was cheaper than the Eurotunnel

Hope this helps 

You allowed to carry up to 1000kg of personal belongings you had them over the year if you're driving the van yourself.

Saving 350km comparing to Dover crossing but it's 8 hours sailing? Never worked for me time wise.

No matter when you bought the tickets, all matters that you need to submit API in advance before the crossing. As you're  allowed to submit oral customs representation , full van could be checked for illegal substances or goods (money?), three cats could act suspiciously so need to bear that in mind and it's normal. You could be stopped in the middle of France by customs and maybe you will, don't need to panic unless you have a real reason to be worried.