Thanks for all the information.

So if the college has this single ADSL access point coming in, and are wirelessly piping it out to 15 centres, it must be on a server, no? And if so, then they will need a static IP, PAT and multiple IP addresses?

Or what if they simply connect the ADSL link to a wireless router... would that automatically allocate the IPs and therefore they'd have no need for PAT and multiple IP addresses?

Sorry if my understanding of this is very very flawed