I was told what the starting salary would be after being offered a position.
Also, this
is rubbish. Yearly pay rises, plus extra pay if you take on extra jobs (not necessarily extra hours, just being trained to do more e.g. till controller, supervisor etc) are commonplace. You probably won't be able to 'negotiate' it as such, but that doesn't mean that everyone is paid the same, it varies with responsibility and time spent working there.
For example, I started out on £4.70 ph or something, then up to £5.40 or so when I completed my training, and now up to £6.30 after a yearly review. I'm expecting another (£7 please!) in a few months

Good wages for a student, especially when the option to do overtime arises as well.