You can either drive or use Brittany ferries who have dog friendly cabins, or kennelling.
If you drive use booking.com to pick places to stay that are dog friendly, there are many in France and Spain.
Once you get to Spain You will have to take them to a vet, as they are on the Spanish Dangerous dog list (Perro Peligroso) who will register their chip over here. You will also have to have Civil liability Insurance of no less than €120,000, you have to obtain a licence for them from your local Town Hall, and take a test of " a physical and psychological examination must be carried out that proves that the person who is going to receive the license has sufficient visual, auditory, locomotor and neurological system capacity"
Plus they have to be muzzled in public spaces, and walked on a lead no longer that 2 metres