What is the best accommodation in Cardiff next year for a mature student?

Looking for some advice so thought there'd be no better place to ask than fellow students. I'm a mature student with a differed offer for Cardiff University (taking another year out to build up my finances) and I'm looking for some advice. I'm really not too fond of the idea of sharing facilities and would like an entire place to myself, so I'm looking for suggestions as these Accommodation websites are a nightmare. I prefer somewhere quieter, away from the Cardiff Royal Infirmary preferably (my partner's accommodation was right next to a hospital and the sounds of ambulances in summer were torture with the window open), self-contained with no flatmates so either a studio or a one-bed apartment/flat, with money not really being an object as that's the purpose behind my deferral; to be able to afford to live comfortably while I'm in University. I'm not looking for the halls experience as I live 15 mins away on the train and don't need flatmates to socialise with, and would prefer somewhere private to spend time with my partner (so a double bed minimum is a must, no 3/4ths). I'd also like to be able to walk to campus but I wouldn't be averse to a short bus ride. Also, I've heard the Uni Halls aren't to great and are especially far so I wouldn't mind giving them a pass unless there's some gems amongst them.

I know this is a rather particular requirement, but I was really hoping for some help on the topic. Just to bullet point it;

>Studio or 1 bed Flat/Apartment of decent size
>Double (or preferably King) Bed, and preferably no strict rules against guests
>20-ish minute walk from campus, or a regular 10-15 min bus
>Private and quiet, preferably geared towards postgrads or mature students
>Good Internet would be a nice plus

This isn't until next year but I'd love to get in early, any help would be much appreciated!