Every freaking year.
The NSS which measures student satisfaction very very badly is every year; the Times Higher Education World University Rankings which measures everything better than most other similar rankings ditto, and the REF which rates just research is every 6-7 years.
The Guardian guide should be taken with a MASSIVE pinch of salt because it does not include research in its rankings, when research is a massive part of what makes university university, and university teaching on a whole other plane from school. Use the other newspapers.
That being said all the university league tables are really only rough guides. It's rare for a university department to entirely move out of top, middle, or bottom, but it is very common for it to move several places up and down, depending on those two disgruntled students whose single lecturer for one module in their final year was absent for two weeks with the flu and neglected to give the substitute proper instructions because they were at home vomiting .
So look at the cluster of universities that are consistently in, say, the top third of the table for your subject of interest. Then look at their offer - if they say three As, they mean it and you're unlikely to get in otherwise so no point prioritising it if you're not a 3 A student.
Then look at the departments you like the look of and see if you like the profile of the lecturers and senior lecturers (who generally do tend to teach undergraduates) and the elective modules on offer in years 2 and 3 (and 4 if it's an MSc) to see if you like the subjects and think they might lead on to something interesting career wise (or otherwise!). You should also be able to glean from those modules who the lecturer is and therefore whether or not the world-leading professors advertised as a big draw do, in fact, teach.
Cost of living is likely to be a factor; London is obviously expensive but has lots of part time work and other career boosting opportunities; big cities like Manchester, Leeds, Newcastle, etc are much cheaper to live but also have plenty of PT work. Oxford and Cambridge are both a LOT cheaper to live in for students than the usual surveys that are done by the likes of HSBC - some of the cheapest rents (and much shorter terms), heavily subsidised meals and alcohol, no need to use public transport or drive, etc, etc, etc.
And then there are all here subjective things - big, small, nightlife, urban, country, etc.
But the most important thing is that you choose the best quality of course for the grades you can attain.