Was his school actually ever mentioned in the story? I seem to recall this discussed once long ago and it was decided it may have been created for the mini-series.
I'm just checking Darcy's letter and it mentions that Wickham went to Cambridge (don't know how long) but doesn't seem to mention if Darcy was there. In all likelihood he did... just being nit-picky, I suppose. ;)
He said he had opportunities to see him in unguarded moments, not necessarily at Cambridge, yes. So probably Mr Darcy went to another university. Maybe there was another one of greater name in those days. Any ideas? Oxford, perhaps?