Right, I've set up a VM and installed and configured AD following the structure suggested above and it seems to be working quite well.
One thing I've also tried out is delegating password management to Teachers on the test domain and asked a member of staff to test this, however, although resetting a password in ADUC is extremely simple, the member of staff in question seemed to have real trouble and would prefer a dumbed down version! Perhaps the bespoke software would be a good idea...
By the way, how stringent are you guys with setting GPOs for Staff? I generally completely lock down the desktop for Pupils, however I'm not really sure how strict I should be with staff.