No problem.
Having a gap year and taking time out of 'normal' life is a great thing to do.
Remember that the first year of uni doesn't count towards your final classification. This year is intended as the time for students to find their feet and 'grow up' so I wouldn't worry about not being mature enough.
Also consider the impact of some friends possibly moving out of your area and you being left behind. I know someone who took a gap year and felt a bit isolated in his small town after his friends moved out to uni and work.
I also have a friend who had a gap year but then dropped out of uni in the first term. Not the end of the world but I guess he lost a bit more time. I think it puts more pressure on you to get your uni choice right first time.
Travel, work, read some good books, get fit, get drunk. Just make sure you have plenty of constructive, rewarding activity to go alongside the duvet days.