Tilly and the Time Machine by Adrian Edmonson
Tilly is seven and a half - and about to make history. When Tilly's dad builds a time machine in the shed there's only one place she really wants to go: back to her sixth birthday party, when she ate too many cupcakes and her mummy was still here. But then something goes wrong! Tilly's dad gets stuck in the past and only she can save him ...Will they make it back in time for tea?