It's a well-known fact that those who take a gap year are less likely to drop out of University during the first year. Universities like students who take a gap year for this reason, and also because they tend to be more mature. Employers no longer employ people solely on the basis of their qualifications. Life skills - such as decision making and living independently that should be gained on a gap year - are seen as more important.
Totally agree with the answer above. As a Careers Advisor if you are thinking of taking a Maths degree for example some prefer you not to take a gap year until after your course. However to get round this, you will have sufficient time off from when you complete your Level 3 course i.e. A Levels etc to when you start university as most courses start in October (although not all!) that you could in theory do Gap Months as I like to call it.