Gap years don't hinder uni chances. Indeed, my uni effectively made me go and have one!
In fact, gap years will positively enhance your chance of getting into uni if you are doing something related to your course (and write about it in your PS!). For instance, if you're applying for medicine, then working as a healthcare assistant will do wonders for your application. If you're applying for politics, then some election campaigning will also have a positive effect. At the very least, you need to do something productive - getting drunk in your hometown for fourteen months isn't going to enhance your application one iota.
However, universities don't expect you to spend all your time doing something excessively worthy - there's still plenty of room for some lazing about on a tropical beach!