Firstly Spain is in no better a condition now than it would have been had it allowed a vote and campaigned and lost.
Secondly, a more accurate UK comparison would probably be with the Scottish referendum, which was won by those who wanted to remain part of the UK and so Scotland did remain part of the UK.
I don’t think that’s true. The violence that occurred on the day of the vote and the uncompromising attitude of the Spanish govenrment likely caused things to escalate more quickly than it would have otherwise.
Secondly, a more accurate UK comparison would probably be with the Scottish referendum, which was won by those who wanted to remain part of the UK and so Scotland did remain part of the UK.