A delightful gallery. I went here on a coach trip in March 2012, and I was pleasantly surprised. It's rather difficult to find, tucked away in the university library. I've been to Leeds lots of times without ever coming across it, but it's worth checking out. It's quite small though.
It's free to get in, and is open Mon - Sat 10am - 5pm, although it is closed when the university is closed.
This is probably only a gallery for art lovers, rather than passing tourists.