Yup - I also have taken a 'gap year' of two decades!
Three weeks into my Equine Management Degree course - though I have been lucky enough to be able to take the plunge and do a full time course.
It is scarily cool - a bit like a car crash really - frightening at points but you still get sucked in.
I've got to do work experience after Xmas break - for three weeks. I last did that when I was 16!
The main piece of advice that I found useful was find somewhere at home to study, and if you can, try to have as little 'pollution' from the rest of your life there as possible.
Easy to say, strangely hard to do - espescially if you got kids etc. It's sooo tempting to sit and re-work lecture notes whilst half watching the TV.
Oh, and I was told to try to set a routine and get others to help you stick to it. My first half hour when I get in is dedicated to a cuppa, my day's notes and my laptop. I type everything up, print it and file it. It's strange how much seems to have sunk in just from re-working notes. The door is closed and everyone (mostly the phone) gets ignored until I'm done.
You may also surprise yourself with how much comes sneaking back in from days of old. Ask me what I did in school biology lessons and I'm stumped, but during a lecture stuff that I thought would be difficult is often actually making sense.
After all that, what are you studying?