Hello Ed,
Heading to Spain also end of April. Heading for JerezGP.
Have you looked into the new Brittany Ferries service from Portsmouth - Santander? Been getting good reports over the old, slow and expensive P&O ferry (Bilbao). Me and a bud, £100ea for two sharing. (The ladies are being put on a plane over
while we "endure" the "hardship" of a long trek down.
)
It is mostly m/way blasting unfortunately, not usually the way I like to go, but a means to an end...well , Spanish moto madness is not to be missed.
But, we are going to cut along the coast similar to yourselves and then head south from Panes - Potes. N621 The Defiladero de la Hermida, which skirts the east of the Picos. This stretch off road has been raved about, the latest example being in BIKE mag last year. Might want to figure that bit in on your trip? Although your spoilt for choice here.
Also shadowing your plan from there to Aguilar De Campoo then the fun stops to head south on the m'ways for a stop in Salamanca.
Was planning a 2 weeker in the Picos next year. Be interested to know how you get on and your choice roads.
Have a good one.
Andy