Jobs and careers
Careersbox - gives you in-depth information about different types of careers from the people who do them.
Horses mouth - will link you to mentors going different types of jobs - the next best thing to a work placement.
Courses, training and apprenticeships
http://www.ucasprogress.com/ gives detail of all the different courses, schools, colleges and work based learning across London
If it's apprenticeships you're after, this is the site for you: http://www.apprenticeships.org.uk/
To find out more about university visit http://www.ucas.com/
Part time jobs
Central London Connexions
Provides information, advice and guidance on courses, careers, jobs and training opportunities for young people aged 13 -19 years (and up to 25 years for those with learning difficulties or disabilities).
If you're still not sure, why not try your skills at volunteering?