I’ve been in sheffield last year and my tip for those who need accommodation from July to September is Opal One.
Opal is probably the nearer hall of residence, just 2 blocks from West Street and Tesco. I used to live in Endcliffe Village too and that one is quite far away and up the hill.
Opal One is always fully booked for the academic year (and for the next couple of years too) but there are plenty of rooms available during summer break.
And the best of all is that you can get a good discount. Talk to Richard, the manager at the reception desk. Tell him that you know Luis, the Brazilian guy.