Find further study: what type of course?
Pure research
Either three/four years full-time for a PhD, or one or two years for a Masters. Some PhD schemes offer the chance of finishing after one year with an MRes. Many different organisations provide support for postgraduate research. For example, see the Research Councils UK web site to see who supports work in your area of interest.
A few research programmes include other training, such as the EngD. Knowledge Transfer Partnerships is a scheme where universities and employers offer a paid job in industry combined with a research degree.
It is worth checking the relevant research council websites for the latest details of research training programmes.
Taught Masters
Either one or two years, including a dissertation. See Prospects.ac.uk for a database of courses and research opportunities available in the UK.
Diplomas and Certificates
Usually vocational and lasting an academic year, occasionally two.
To find out more about courses, see How do I choose a course?

