What jobs are avaliable in the UK building profession?

I want to get in to the management side of things but first want to learn the grass-roots practical aspects of working on a building site.

Which jobs on a building site require no previous qualifications? Someone told me a hod carrier is the lowest ranking, so to speak, so could I just walk on to a building site after a health/ safety briefing and start work as one of these? What about a labourer or a brick layer?

I have heard you now need to take a course to be a bricklayer- if so, how long does this take and cost, roughly?

Thanks!

Laborourer,plasterer,brick layer.

General labouring is the unskilled entry level, brickies need have qualifications.

As for just walking onto a building site, that won't happen.

Best option would be to find an employment agency specialising in the building trade
Have worked as a labourer in the past, but only on an ad-hoc basis for a family friends company so didn't have all the hassle that normal workers will have.