Its really not very far, just under 3 miles., so walkable in about 40mins. The 80 bus also runs regularly throughout the day. It does stop at around 11.30pm, but as l3ann3 above says, the saftey bus runs until the early hours of the morning. I've even walked it at 3am when I missed the saftey bus and it was fine. My friend walked it at all hours of the day and night when she was coming back from the library. But if in doubt, the saftey bus is the way forward.
I've graduated now but lived in the Oadby student village for all three years of my degree. I absolutely LOVED it there and given the choice again, would stay there with no hesitation whatsoever.
Please don't decided against Oadby just because of the distance. Its not very far away and are plenty of safe options for travelling at any time between the campus and halls.