Hi!
As far as I understand it, the University of the Arts is just a network of six constituent colleges of Art in and around London. You would be better looking for rankings of the particular college you wish to apply to (Central St Martins/London College of Fashion/Chelsea College etc) , as I believe that is how they are normally listed. (Pretty much the same as the 'University of London' colleges all being separate and treated as such).
Hope that helps