mate, first of all... good luck trying to find a flat there :P
Wroclaw's the biggest student's city in Pl, and one of the fastest growing cities in the country as well, so getting a flat is no easy thing, you can try to rent something meant for tourists/short-stays in websites like:
or... you can try these local sites, all in Polish, but you'll find better options for you, since they're meant for local students and workers:
- do a google search with "mieszkanie do wynajęcia wrocław"
small (rather big) advice:
- DON'T check flats in "Huby" zone (just south of city center, east of University of Economics)... not a nice place
Try to get some local (and trustworthy help) if you can. If not, and you'll find yourself in some trouble trying to get accommodation, pm me, I can help you out since my wife's from there