Like what opportunities/support do they give to students who do music related stuff there? Not counting their degrees in music. Is it worth it?
From a classical musician perspective: if you mean music societies / performance opportunities for non-music students, it's very limited. There are a few student run societies - jazz band, concert band, string orchestra, big band (look on the SU website for these) but these are of a relatively low standard. There's the university orchestra but you will only get in if you're a music student or play a string instrument.
If you're a music student, there are plenty of performance opportunities, and I think you will definitely be part of some music group because it's part of the course (i think, don't take my word as I'm not a music student).
Also, you can't book out practice rooms unless you're a music student, but you can book out the teaching rooms, and I believe there are a couple of rooms that have a piano.
There are lots of opportunities to get involved with music societies, including Concert band, Big Band, Gospel Choir, Jazz Orchestra BandSoc and String Orchestra. You can also start your own society if you choose to as well! Studio X is a concert featuring the bands and singers at Surrey held across the year and in the summer there is also the opportunity to perform in FreeFest, which is Surrey’s own festival in the summer held by the lake!