No, you are not. In fact, you'll get a lot more out of it than most of the 18 year olds, who often attend college because of parental pressure, or found they got the grades for a prestigious course they have no real interest in; you have made the choice to go, and that alone will make you more motivated and interested.
I taught at college for nearly 20 years, and I can say that teaching adult, or "second-chance" students was - personally and professionally - by far the most rewarding - and challenging - of my teaching career. Actually, the first time I taught a class of "adult" students, I was shocked to realise that I was the youngest person in the room; my task then was to win their respect.
No age is too old to learn, or to embark upon a course of study that interests you. My mum went to college in her 40s, loved it, and always said that it gave her the confidence to apply for positions she would never have had the confidence to apply for (although she had the experience).
One of my closest friends, who is in his mid 40s, was made redundant last year, and has just started a BA and finds that he loves every minute of it. Indeed, it is something he had always wanted to do but the opportunity never arose until now.
You'll have great fun, an intellectually rewarding journey and socially enjoyable time awaits you. Go for it.
Cheers and good luck
