I found this book on a shopping website. I know which shop but the problem is that the shop isn't returning the book when I search via the site's search bar when I try to find it again.
The front cover of the novel shows a unicorn stampede, with a blonde girl between the stampede and the viewer, her back facing us. I think she's standing on a cliff.
Perhaps this is A Plague of Unicorns (2014) by Jane Yolen.
In this historical fiction-meets-fantasy novel by award-winning author Jane Yolen, readers 8-12 will experience a world where a young boy with nothing but questions may have the only answer to solving a unicorn infestation at a medieval abbey.
When young James asks one too many questions, his mother and uncle hope an education at Cranford Abbey will make him a proper noble—but when James arrives, the monks there are most interested in keeping the unicorns in the orchard from eating all the prized golden apples they need to save the abbey. Abbot Aelian thinks he knows how to defeat the ravenous unicorns, though it may actually be up to James to use his inquisitive mind to find a way to save Cranford Abbey and hopefully find a way to return home.
The cover shows a blonde boy viewed from the back, a stampeding herd of white unicorns and the golden apples.
