Hiya!
Current student here, and congrats on your offer!
Honestly, Cardiff is great if you want a bit of the city, but also like a quieter/more nature-y vibe. The campus is right next to city center and its always busy especially when there's a match on, but everything is at a walkable distance and there's loads of parks dotted around. In first year, I think I only ever had to take a bus like once or twice haha.
The School of Law here gets up to some really cool stuff - as a student, you can take part in things like the
Pro Bono Unit and other bits of work experience.
When it comes to accomodation, honestly it depends on your budget and you preferences, since there's loads of different places to suit individual needs. Do you prefer shared bathroom or ensuite? Do you prefer to live closer, or prioritise a bigger room more etc...
In general though, I've enjoyed living here! Accomodation is much more affordable than other places in the UK, which is a plus

Let me know if I can help answer anything else

~ Fatiha, Cardiff University Student Rep