Gilly, obviously you know your daughter best, but I'd have thought 'studying' would be more like to put off a not so academic child. However, it's great that she is showing an interest.
My suggestions are as follows:
Josephine Tey: The Franchise Affair, Brat Farrar and A Daughter in Time;
John Wyndham: The Chrysalids, The Midwich Cuckoos and The Day of the Triffids, which someone else has already mentioned;
Vera Brittain: Testament of Youth;
Evelyn Waugh, Brideshead Revisted;
Arthur Conan Doyle: any Sherlock Holmes;
Margaret Atwood; Oryx and Crake trilogy;
Philip Pullman: Northern Lights trilogy (if not already read). My ex English teacher sister used to recommend this for reluctant teen readers;
But I would try and find something that reflects her interests. Is this the daughter at music school or another one? If she likes music she might enjoy The Mozart Season by Virginia Euler Wolff.
Brat Farrar would be especially good if she liked horses (or try The Horse Whisperer by Nicholas Evans).
What film/television does she enjoy? Might she enjoy the Poldark books? Has she read The Hobbit or Lord of the Rings? My Family and Other Animals? (one of my favourite books at that age). What period in history has she been studying (and did she enjoy it)?
Has she read any Eva Ibbotson? If not, try The Star of Kazan.
Malorie Blackman's Noughts and Crosses series?
Watership Down by Douglas Adams?
Kes by Barry Hines?
I Capture The Castle by Dodie Smith?
Masses of good children's books by Michael Morpurgo that she might enjoy if she hasn't already (try Private Peaceful and War Horse)
If you're going for Classics, I'd start with:
Anne Bronte: The Tenant or Wildfell Hall;
Wilkie Collins: The Woman in White;
Dickens: Oliver Twist, David Copperfield, Nicholas Nickleby or Great Expectations;
Eliot: The Mill on the Floss
Hardy: Far From The Madding Crowd, the Mayor of Casterbridge or Tess of the D'Urbevilles.
Have fun. There's so much to enjoy!