Taking a gap year can make you more attractive to employers.
According to a British government report by the Public Accounts Committee, students on engineering course are more likely to drop out than any other course (except maths and computing).
You can keep yourself motivated on your course by taking a gap year before you go to university or by having a year off midway through your course. A year out before you actually begin work is also a way to keep you inspired. Doing a work placement or voluntary or paid work in your gap year will increase your employability and make you stand out from other applicants as you will have learned valuable new skills. Showing a commitment, arranging and sticking to a project will show you have project management skills and are willing to fulfil responsibilities.
"Year in Industry" is a scheme where you can work hands-on for an engineering firm and get paid at the same time, taking a year out between your A-levels and degree. This can offer valuable experience which can give you an advantage over other applicants when applying for permanent jobs later on.
Of course, your year out can be a way of taking a complete break from the engineering course or work that you do and do something totally unrelated. There are many companies that can help you find voluntary or paid work doing community work or teaching abroad, or working with conservation for example.