Not cheap, but well worth doing.
Ferry overnight cabin from Pompey to Le Havre and overnight cabin return from Bilbao £650 with Brittany Ferries.
2nd week in June was spot on.
Camp sites are all up and running for the new season, but still quiet. Always found somewhere to stay when not wild camping. Just before the big heat to.
Blessed with great weather on the Spanish side for the whole trip to.:thumb2