Bloody hell, it's ATCO selection, not a spotter's course!
They don't want to know if you can name the manufacturer of the catering trolley on a 747-400. They want to know that you recognise it is a 747, how far it goes [inter-continental would probably suffice], how many poor wee buggers are expected to fit into it [roughly], who operates it [not all of 'em], where it could be expected to be seen in UK [I would venture that Inverness doesn't see too many] etc etc.
ATC is a holistic thing. If you just learn the numbers, you ain't actually learning. You need to read between the lines so that you
understand