I suppose the best starting point for things Scottish has to be the music of the much maligned Corries. Up to the time of Roy Williamsons untimely death, they made umpteen records and recorded practically every Scottish popular song worth singing. When they were good they were unbeatable, when they were´nt - at least you learned the value of C,F and G in traditional music! And they were responsible for Flower of Scotland......well, somebody had to be!
The absolute guru of Scottish music is Dick Gaughan. His records Kist of Gold and Handfull of Earth are among the best folk records ever. The same goes for Archie Fisher´s Will Ye Gang Love. Back on the popular front, The MacCallmans have been pretty prolific over the years and are a good source of trad. Scots stuff.
Of course there´s a lot more - electric, acoustic, unaccompanied, instrumental......much better than Irish music (not that Im biased *ggggg*).
Lang may yer lum reek,
Jock.