This is at the Royal Northern College of Music, an ugly concrete and brick thing on Oxford Road. It's just across Oxford Road from the Commonwealth Games pool, north of the Precinct Centre (a big red brick thing that bridges over Oxford Road), into town from the main University campus. It has a lot of building work on, so there's scaffolding and blocked-off bits. A simplified map is shown on the right.
If you're coming in by bus, get off at the Precinct Centre bus stop (see map) and walk round the corner. From the main University campus or the Students' Union, just walk up Oxford Road into town. The entrance isn't actually on Oxford Road, but on Booth Street West: the blue blob shows the entrance: