IME the DSA people actively try to offer stuff to help (unlike any other benefits) - DD has a medical condition which causes fatigue and brain fog, as well as the high possibility of missing lectures. She was offered voice recognition software, reading out loud software (can't remember the actual name of that). Also, if the uni hadn't already set them up, allowances re assignments and exams (she gets automatic 2 week extension for assignments - that's department specific, and she can resit an exam in the supplementary exam period as though it's a first sit). Special library permissions (I think no fines for returning books late, plus they'll send someone to find a book and bring it to her).
Definitely worth applying, make sure she has plenty of medical evidence as to how her migraines affect her (frequency, duration, how long she's wiped out for afterwards). In our case DD was getting DLA, but she submitted lots of medical reports, and her school care plan (some of her stuff is around safety).
Other people she knows get a taxi allowance (reimbursed after the event).
Oh, she also gets a printer, paper and ink, so that she doesn't have to go onto campus to use the printers there.
Another think to think about is which halls she chooses - Birmingham (where DD is) had an option to pick "morning person" which meant that her flat was not a party flat. We also read all the reviews carefully, as some halls are livelier than others 
. Distance from lectures might also be a priority - if DD is unwell, she needs to get back home asap, that might also be the case for your DD, depending on how much notice of a migraine she gets. I can't imagine being ill, and still having a 30 minute walk to get back to bed, or worse, a bus journey. I think Birmingham gave priority booking for halls for disabled students.
Its easier to sort everything out beforehand, especially since software comes with training. DD however had decided that if she got in to uni, then she'd miraculously be better, and wouldn't need any of this stuff [sigh], so she's still trying to fit in the training sessions, half way though her degree.