As the person above said, 1 year is nothing. What's your rush?
Who cares whether you're behind your friends? They aren't all at one university are they? waiting for you to go and join them?
I started uni a year late as I did an art foundation before I started. There's more people 19+ than there is 18 year olds from what i've seen. And now i've all but decided that i'm going to switch course, perhaps university if I can't switch internally, so will be starting again at 20, or if I have to take a year out to reapply then 21! And after being at university, I know that the fact i'm a couple of years older won't make a difference at all.
If I could of known before I started university in september that I was going to want to change courses before the end of the year, then I wouldn't of gone. I could of saved myself a lot of money, earnt some money, travelled, done some re-sits. Whatever I wanted. Instead all my time was taken up working on a degree that i'm not finishing.