Very varied depending on the uni and you on the person (and their condition(s)). At the worse end of the scale you have a faculty meeting for student reps organised in a 3rd floor room inaccessible to the rep who uses a wheelchair. I've also experienced (at my post-grad uni, which I don't name here) a university defends its policy to leave students in a room when they are aware there is a serious risk to life, and defend the case where I very almost died.
Other unis are awesome and even arranged transport and accessible accommodation for me when I went to interview there.
There's a scale, depends on the uni, the person, the disability. Some of the experiences I highlight are 8 years ago now. Others more recent