I think Dave makes a good point, nsr's arent for mile munching they are for thrashing around twisty roads. If you got the plymouth to Santander ferry we could spend 3 or 4 days thrashing around the hills and mountains of north Spain rather than 3 or 4 days travelling to and from somewhere on motorways
I would love to go to the Jerez gp but I think this is normally in March and most of Spain is still quite cold plus the fact Jerez is 989 km from santander or 2135 km from Calais.
Thats a lot of back ache on an nsr.