aussie working holiday visa into student visa.

On an Australian passport, does anyone know if is it possible to go to the UK on a working Holiday visa, and then swap to a student visa? Can you stay in the country or do you have to leave the UK to apply for another type of visa? I have been accepted onto a masters course from Oct 2009 and want to go over to work and save money in pounds and settle myself a few months earlier. I have tried getting an answer from the office in Canberra but not having much luck. Any suggesstions appreciated.
My overall idea is to use the working holiday visa first, the student visa next and the post study or highly skilled migrants visa when my course ends. But not sure what the process is.

See also 12.3.1 - Mandatory entry clearance requirement for students.

When the WHV ends in November to be replaced with the Youth Mobility Scheme (Tier-5), it appears from the Border and Immigration Authority website that under the new scheme you will no longer be able to switch in the UK to any other immigration category. You will be able to confirm whether this will in fact be the case when the full rules are available.