I see you've used the word busy/busier in each one of your posts. There is a distinct difference between handling busy traffic and handling complex traffic. Sheer numbers don't mean much. There are a number of smaller, primarily GA aerodromes that don't provide ATC that are 'busier' in terms of total movments than many of the larger aerodromes in the UK, with ATC, controlled airspace etc.
The college works to a regulatory standard, and anyone who meets that standard gets a Student ATCO licence. If you're thinking that someone who is a borderline pass will get sent to a backwater aerodrome with a handful of flights a day, and the 'cream of the crop' gets sent to a large London airport, then no, this isn't how it works and that view will grate on some people if its implied.