As I am married to a Spaniard, I am automatically considered a fiscal resident.
I don’t know if that is right, but obviously you had better check with a tax lawyer.
I hear that these days there are lots of Spanish bankers (think Santander) who work in London Monday – Friday, then go home to the family in Madrid for the weekend, yet pay non-dom UK taxes on income. Very sweet deal. They are all Spanish, married to Spaniards, with family home in Spain.