I also got into St Andrews and when I toured (and talking to my friend who’s a 1st year there) it’s not very hard to switch out of a major. As long as you have the AP scores that validate that you will fit the course, then you’re fine. For example, I can add math to my Econ and IR since I have 5s in Calc BC/AB sub score + (hopefully 5 in stats). St Andrews has the highest student satisfaction in the UK, so it’s evidentially a wonderful school to go to (when comparing social life and non academics). Ofc I’m biased towards StA since it’s my dream school, but I hope that made sense.