Witchworld (Witchworld Series #1)

Flo is a thoroughly modern witchgirl. She has a spellstick, travels about in her skyrider and wouldn't know a cauldron if she fell into one. But when her grandmother turns up on an actual boomstick, warning that ghouls are about to attack Witchworld, Flo realises that everything she's been told about being a witch is just hocus pocus...