The Apprentice Witch by James Nicol

Arianwyn fluffs her witch's assessment. Awarded the dull bronze disc of an apprentice - to the glee of her arch-rival, Gimma - she's sent to protect the remote, dreary town of Lull. But her new life is far from boring.

Turns out Gimma is the pompous mayor's favourite niece - and worse, she opens a magical rift in the nearby forest. As Arianwyn struggles with her spells, it's soon clear there's much more than her pride at stake ...