There is now widespread recognition amongst University Vice Chancellors, admissions staff and employers, of the positive impact of a constructive year out. So much is learned about yourself and key skills are developed. It has become increasingly popular for 18/19 year olds to take such a 'year out' after finishing A Levels or Highers.
Students apply as normal for a place at University and when they are offered a place, the choice can be made to defer this offer until the following year, and to keep this place safe, others may have secured training or a job for the following year and may even receive support from their employer.
There is a wide choice of projects to participate in this year, some of which exclusively accept those on a gap year of this age group. The author took this route after finishing A Levels and took part in a marine conservation expedition with 'Frontier' to Mozambique, it still remains as one of my biggest achievements and was a great experience.
One major factor with most of these expeditions/projects is that there is usually a fee which has to be paid in order to take part. This varies considerably and is usually quite significant if you are planning to go for over 2 months. Fundraising, planning and realistic goals are major aspects of raising the fee, and is a major learning experience on its own.
Various Possibilities for Gap Year projects are listed here and also links to useful resources