Hello,
This is Jon Ellison, Creative Writing student, Masters. I read your message. I'm a mature student myself aged 29.
I know other students on my course who are above my age. One of them is in his 40s. Another is in his early 70s. We've had some social meetings and the uni opens doors to people of any age, 18 and above. So you won't be excluded from social events or uni life in general.
When I started my undergrad, I was 21. But a few others were above my age.
True that most uni students are aged between 18-21, but there's nothing to worry about.