Therefore, its known narrative elements are not a part of the Doctor Who universe as we, on this Wiki, choose to define it. It may have been the basis for a similar story in another medium, however — and that story may indeed be valid.
A World of Her Own was the first children's novel in Paul Magrs' planned Tales of Hyspero trilogy, set on the planet Hyspero from his 1998 Eighth Doctor novel The Scarlet Empress. It was described as "a Magrsian look at the Narnia mythos", with "REAL kids discovering a magical land." Despite being set to be released as a 288-page hardback book by Simon & Schuster Children's Books on 6 September, 2004, A World of Her Own was never released.
A Narnia pastiche set on Hyspero would later appear as a plotline in Wildthyme Beyond!, possibly repurposed from or inspired by this novel.
Lizzie is furious that she hasn't travelled to another world and had adventures of her own yet - after all, everyone else in her family has. Then she and her best friend Tom discover Hyspero, a land of magic, which changes all the time...