Welcome back, you will soon wonder why you ever gave up! There is quite a few of us who gave up in our late teens and have made a bit of a comeback to racing.
It doesn't matter if you can't race every week, just race as often as you can. I'm not sure why but saturday racing isn't very popular and I don't know the clubs around your area so I can't advise on when they race. My club (hinckley) races on a saturday afternoon but it's a bit of a trek for you.
I've tried TC and off road and I prefer the bumpy stuff, TC can get very expensive buying tyres all the time and it just doesn't seem as much fun as getting some air over a table top.
Check out the BRCA club list and go along to your nearest clubs and have a chat and see what they are running.
http://www.brca.org/?q=clubs be careful though as you may have a few deliveries arriving very shortly after
