Doing highers from home? Watch
I'm self-teaching Higher Human Biology this year (I was unable to get into an evening class and I'm already doing a FT HNC course) and I have to pay to sit the internal assessments and the exam.
Yes you can self teach the subjects and then sit the unit assessments and final exam at a college. I'm doing this with 2 of my highers this year at a place called Wallace college in Edinburgh.