Moving to scotland as a english college student

Hi! I’m a Scottish student in my final year of high school. How the Scottish system works is that we have 3 different exams taken over the course of high school, but only the latter two matter for university. National 5’s are learnt from S3-S4 (sat at the end of S4), Highers are learnt over the course of one year and sat at the end of S5, and Advanced Highers are the same but in S6, the final year of school (I’m currently studying my advanced highers! They’re kind of our equivalent to A-Levels. Most people take three - I’m doing English, Music and Mandarin). I hope that helped - let me know if you have any questions!

So since I have left English high school some time ago now, what would my next steps be towards even doing anything similar to what I was at college? I'm having issues attempting to understand where I would be slotting myself in and even if I would be able to due to the fact I'm 19.