The QS rankings do cover a well rounded list of components.
However 50% of the QS ranking is based on academic reputation in the form of a rather loose survey of academics. This can easily be gamed, although you cannot vote for your own affiliation. Another 20% is based on graduate employability as discerned through a similar survey of employers.
Rigorous, QS is not.
The Shanghai Rankings (AWRU) are research orientated but have solid metrics behind them. Research is also one component of the CUG. IMO the latter is the best UK specific league table. In contrast to my general reading preferences, I also rate the Times league table higher than the Guardian’s although I think there is some point to the latter’s choice of components.
OP, I would look to see which degree programmes in the CUG (or UCAS?) your DD’s PGs match well to the entering grades for last year.
Keep in mind that in some very competitive programmes, the standard offer is only made to applicants whose PGs exceed it. (I am a former Russell Group STEM admissions tutor and I highly disapprove of this practice, at least in the absence of further tests or exams)
Also, if ‘FM is strongly recommended’ or words to this effect, then applicants whose schools offer FM may be expected to take it.
Admissions tutors are generally happy to help. Your DD should feel free to email with any questions concerning FM or whatever. She can contact anyone on the admissions team and they will route the message to the proper person.
(It isn’t a good idea to ask about the ‘true’ admissions requirements as I have discussed above, however. The process I described is done by units of admission that aren’t ready to raise their entry requirements for whatever reason. This isn’t something they will discuss publicly)
Best wishes to DD