"Was there similar international condemnation of Scottish independence?
I do not remember any.
Why has our government defended Spanish unity when we believe in self determination for our own regions?"

Our government fought tooth and nail to persuade Scotland to remain in the UK. There is no difference in attitude between UK/Scotland and Spain/Catalonia. The difference in approach is that Scotland was allowed to have a legal referendum. Spain has said that the sacked Catalan politicians may stand for the regional elections in December. A poor showing by the separatists may, in Spain's eyes, be a way out of this. I have a feeling that the elections won't end the divisiveness.