for a start have a look at:
http://www.brscc.co.uk/default.asp?page=getting-started
for an idea on costs
http://www.msauk.org for more info
Have you done much karting, if not then it is great way to learn to drive, try
www.karting.co.uk and
www.club100.co.uk (arrive and drive series, so you do not need to buy much). Try 2-stroke karting to get an idea of speed, etc you will exeriance in the future.
Hope that is a start.