Our experience is that there can be considerable differences between what universities say about flexibility for mature applicants for creative arts degrees and what actually happens in the admissions process as regards qualifications... however many conversations have been had with admissions and with subject staff prior to application. Keep receipts! Of course nothing entitles an applicant to an offer of a place, but you may have to fight for the advertised right to at least be considered (one university said they guaranteed all mature students an interview... and didn't). Everything does as PQ says hang on the age of the student so when you enquire of individual universities, that's got to be up front information (and keep reminding them). I would personally recommend being very upfront about any disability and disrupted educational history.
My son (also a mature student) has a place for September on a creative arts degree without English/Maths. He doesn't have a Level 3 qualification (FE colleges won't accept him for FAD because no English/Maths!) but he did pay close attention to portfolio content recommendations. My concern might be that universities might feel they have 'nowhere to go' with making an alternative offer of the course 'with a foundation year' if she's already done the FAD... however, if she has secured a place on one, then successful completion may well be all they need to feel confident to offer a place.
BTW do you know about all the funding implications for foundation diploma at FE cf foundation year at university, and the change in the way students are assessed for finance if they are 25 or older?