If you have never worked, or have been out of a job for a long time, doing a work placement can be a great way of getting valuable, up-to-date experience and better preparing yourself for the world of work. It will also improve your CV and can be a good way of making professional contacts that could help your career.
If you are unemployed, you may be able to benefit from work placement opportunities offered as part of the Jobs for Haringey scheme (see above).
If you do not qualify for support under the Haringey Guarantee, the Directgov website has a range of useful information about how you can set up voluntary work placements, and make sure you get the most out of them. If you are interested in working in the public sector, for a charity, or even for an MP, you also might find some interesting internships advertised on the w4mp website.