Easyjet fly from London Stanstead (STD) to Asturias airport (OVD) 1 hour by car from the west or to Bilbao (BIO) 2 hours by car from the east.
The flights to Asturias are daily during the summer (Between March and October) and four days a week (Monday, Wednesday, Thursday and Saturday) during the winter.
Further details on www.easyjet.com
Ryanair fly from London Stanstead to Santander (SDR) 1 hour by car from the east.
The flights are daily during the summer and on Monday, Wednesday, Friday and Sunday during the winter. Ryanair also have flights to Santander from Liverpool (LPL) Further details on www.ryanair.com
British Airways and Iberia have flights from Heathrow (LHR) to Bilbao (BIO)
Budget flights with Click air from Heathrow to Bilbao www.clickair.com
It is also possible to fly from Heathrow to Asturias with Iberia and BA via Madrid or Barcelona www.iberiaairlines.co.uk and www.ba.com

By Ferry

There are ferry services from Portsmouth to Bilbao (P&O Ferries) and Plymouth to Santander or Portsmouth to Santander (Brittany Ferries).

www.brittany-ferries.com and www.poferries.com