We will be 3 adults and two children (12 and 9). We don't have a car and are looking for the most economical way to travel. Plane, boat, train, hire car - or a combination of these? We could leave from any of the London airports or Southampton airport, or from Portsmouth ferry port. Does it work out cheaper to fly to Nantes or Bordeaux? I'd be grateful for any advice from those who've done this kind of journey before, as I haven't a clue where to start!