Also bear in mind that for some courses "rankings" are largely meaningless e.g. most allied health professions courses, where provided they have the correct accreditation in place it doesn't matter whether you graduate from one at the top or bottom of the rankings usually. Of course things like quality of feedback provided by lecturers, student support, and so on are important, but these are difficult to measure in league table rankings - usually they're all mostly covered in the nebulous "student satisfaction" criterion which can so often seem to just be a random number generator...
Additionally for "general" rankings this can often marginalise specialist universities (e.g. the Courtauld which only offers one course and doesn't exist on any general rankings I believe as a result, arguably SOAS although they're "restructuring" away from most of their specialist courses, RVS, etc), and may not give an accurate picture for some departments, which may be better or worse than the "general" ranking suggests. For example, the University of Essex tends to not rank extremely highly in general, but has an outstanding politics department with a very strong presence in research in that field as I understand. Conversely Warwick has one of the top maths departments in the country, and very strong business, economics, and CS departments, which buoy it in the rankings (and students perceptions) a great deal, but by all accounts the other departments there are somewhat more mediocre outside of those flagship departments/courses.