I was pretty much grown-up by the time I attended school in Britain - or as grown-up as I'll ever get.
I found college useful for a lot of other reasons. It exposed me to a great many influences I wouldn't otherwise have encountered, and gave me a lot of time with some very intelligent people whose thoughts are still with me.
Now I have to motivate myself much more than I had previously.
Try to meet as many authors, agents, and editors as you can.
The mass-market paperback, for one, is too expensive.
Even if you only want to write science fiction, you should also read mysteries, poetry, mainstream literature, history, biography, philosophy, and science.