I don’t know how it works in the UK, but in the US wr have what we call community colleges, which offer 2 year degrees, trade classes, and continuing education classes. Night classes in particular have a wide range of students - all ages and backgrounds. The classes generally aren’t too challenging, and are very affordable.
You seem very smart with excellent written communication skills, so I feel like you’d do well at a more challenging university. But if you’re nervous and maybe just want to get your feet wet, maybe you have something like I described nearby?
Being reclusive is a strength, though. Most people couldn’t hack it. It’s sort of like fasting - takes a lot of discipline and feels uncomfortable, but once you pull through the next wave of emotions is epic.
I didn’t say two words to anybody in my classes in 4 years of high school except when I had a class with two of my friends. And I only had four friends in four years. From 1990-95 I used to socialize quite a bit. Also from 1996-99. I’ve backslid these last few years but my psychiatrist and my family assure me I can do it again. And I will trust the people who know me. Last week, I went to a barbeque. Today I talked more than anyone in my support group. So it’s not impossible to teach an old dog new tricks.