in UK, David Cameron gave permission to the Scottish referendum without consulting the rest of the country. The parliament agreed, and it looks like the rest of the country agreed, there were no voices against. Fine.
in Spain, the rules are clear, the call for self-determination is not contemplated in the constitution (like all the countries in the world with a modern constitution), Mariano Rajoy and the parliament can't give permission without reforming the constitution. And reforming the constitution should go through a referendum where all Spain is involved. What is more democratic? I don't know, but I wouldn't call the spanish way non-democratic.
And by the way, about Scotland, I consider them to be independent these days as they were give the right to self-determination by Cameron when he approved the vote. they are sovereign, that is the definition of being independent. They've just decided to stick to the british rules for a while, till the next referendum