yeah, such small detail stuff sucks today.
To or Through Spain, which is EU, as a british Citizen, which is ex-EU(or how ever this is handled todays, I really do NOT follow up on that stuff since a while, sory if i state something wrong), acompanied by a EX-EU member's Hubby.
as above stated, I would ask your british consulate and to be safe also a EU consulate liek the spaniards about your specific case, explaining them in deyail your travel and nationality situation.
Good luck and enjoy the ole home continent.
I had my 2 months summe rvisit with my Daughter firt resheduled for christmas, but more and more tend to reshedule again to next summer, even that i do not like to skip a whole extra year to see my ole folks in germany. we may squeeze in a few weeks via christmas, specially if school would really runonline, there could be a chance for a longer christmas/new years visit without missing out anything school wise, as i heard those geramsn have reliable internet todays, too, lol.
nothing rebooked, yet, still waiting to decide anything, with my daughter's school needs to be the prime factor.