Hi Mark,
At the OU, I did Natural Sciences, working towards a Geology degree, but stopped in my third year - similar to you, the prospect of a residential course was more than I could handle, and I started doing more voluntary work & less home study, and didn't complete the degree.
Now (15 years later!), I'm doing a masters in fine art that's partially residential, after doing a foundation course, and diploma in art & contemporary craft at a small arts college out near Chichester.
Re: the OU, they have quite a lot of short course materials available for free, if you just want to give your brains something to chew over for your own interest. It doesn't count towards a qualification but it can still be interesting.
Best wishes