You’ve nothing to worry about, there will be plenty of other students who have either taken an extra year at college or a gap year, and besides, even if there wasn’t, there simply isn’t a significant enough cultural difference between 18 and 19 year olds that you will be able to tell when your fellow students are a year younger than you, and likewise that they will be able to tell that you are a year older than them - I would actually argue there is zero cultural difference on account of that one year age difference - why would there be?
I mean it’s pretty wild to think you’d only be able to get on with people who happened to be born in the same year as you - can you imagine living your whole life unable to relate or get on with anyone who isn’t your exact age? That would be madness and insanely limiting.
I’ll be going to uni this September at the ripe age of 21, am I worried about there being some sort of age barrier? Not at all! I work with people younger and older than me who I get on with very well, and when I was in college I was in classes with people younger than me, never bothered me or them.