What is the library provision like? I'm writing here from experience in the Middle Ages (1988) when of course nothing was online, but even so for History you need written resources in some form.
Is the library open 24 hours a day and/or is there a specialist history library or history librarian (not a general social sciences librarian)? On my course there were 3 major libraries, they weren't open 24 hours but all allowed you to borrow.
How is the teaching done, is it mostly lectures, class-type groups or seminars? On my course it was a mixture of single-figure groups and small seminars, plus lectures.
How often will she be asked to present her work and how often will she be doing some form of assessed work? For example, if the teaching is seminar-based, how many times a term would she be presenting?
Did she speak to any postgraduates in the department, and why did they choose that university for their postgraduate work?
I presume that you've both had a look at this which could be helpful? I certainly don't think that it's RG or nothing, and if she is personally committed to this course, she stands a good chance of doing well. IMO History is very largely about how much work you do; the teaching and facilities are there to make sure that you can do the best work that you are capable of. So if she is in the right mental space, she should do very well.