You should find a course, and then contact the admission office - and pester them for an interview and/or assignment.
I did this in 2009/10 with University of Manchester - I was 45 at the time. Average O levels in 1981 - one A level, and AS level (remember those!) and an O/A level but that was enough to mean I didn't have to do an access course.
I got a 1st. Stayed at Mcr, did an MA with a scholarship. Now in York at end of Year 1 of a fully funded PhD... and if I can do that, anyone can.
Apply - and see what happens.
who are introverts?