England, Scotland, Wales and Northern Ireland are constituent countries of the United Kingdom. The United Kingdom is also a country. You can disagree, but you're disagreeing with the government and the international community.
The NI thing is different, involving a peace treaty between the UK and Ireland.
The Scottish referendum did not use neutral international observers, and had extremely biased coverage by state media. The BBC itself even tried to stir up forms of violent unionism. (Look up the so called "passionate Highlander", a drunken loyalist type who talked about defending the union to the death "in the name of Jesus Christ".)
"The 45" has a resonance in Scottish history and it is a bit of a coincidence the Yes vote was stuck at that rather than 47 or 44.
Having neutral international observers was a no brainer, but the SNP often seems to trust the system they're trying to break up much more than it should.