1. Get a relatively low paid full time + part time job (im pretty unskilled, no degree, last time I was in the labour force I earned £20k p.a). Do this for 5-10 years, save 75%, retire.
2. Continue along with my business covering my expenses and build stuff. I've rekindled my interest in programming, I could work full time on building web services/mobile apps and hopefully hit on something to provide an income.
3. Get a degree in IT, either full time/part time. Get a job. Save. Retire (i'm not sure I like the time scale in this one or the debt involved).
It looks like your essentially asking if you should:
1. Get a low paying full time job.
2. Build and tinker and hopefully strike pay dirt.
3. Get an IT degree, acquire job, retire down the line.
...whilst keeping your current sustaining work on the side.
To which I advise:
1. Do so if you either get compensated enough to make it seem worth it or if you thoroughly enjoy the work.
- This seems to have the least risk. You try it, you don't like it, you leave and don't look back. It doesn't need to go on your resume if it goes sour
2. Do so if you recognize that while you might hit a home run, an equal chance of making very little money still exists.
- This I'd rank similarly on risk. There's nothing stopping you from combining option 1 and 2 so long as you have time to do so. If you don't like building things, you can just stop.
3. Do so if you are truly passionate about the field and if you can tolerate the time/money setback associated with entering university.
- College scares me if you need to go into debt to attend. There's no guarantee it'll set you any further ahead and in the IT world, it's not always 100% crucial as Sherr explained.
If I were you, I'd combine the first two options and see how they go. If you're unsatisfied, consider all aspects of getting into college. Weigh out the pros and cons.