Connections are very good between the UK and North West Spain, and are improving all the time.
For visiting east or west Asturias, Asturias airport near Aviles is the most convenient airport. You could also fly into Santander airport for eastern Asturias.
Easy jet operate regular flights from Stansted to Asturias airport.
Ryanair operate regular flights from Stansted and Dublin airports.
There are 3 main airports in Galicia.
Ryanair operate regular flights from Stansted to Santiago de Compostela.
The most convenient airport to fly to for Cantabria is Santander, which is located just to the east of the city. Ryanair operate regular flights there from Stansted and Dublin airports