My Unwilling Witch starts a girl band by Hiawyn Oram

Rumblewick is a HIGHLY QUALIFIED WITCH'S FAMILIAR to the MOST UNWILLING WITCH IN WITCHDOM. Haggy Aggy, Rumblewick's witch, has gone star-struck! She's only starting a GIRL BAND and Rumblewick has to be in it even though its clear as moonlight HE IS NOT A GIRL!

Here is what the first page says: 

Dear Diary,

In a zillion moons you will never guess where i am writing this, so I'll tell you - on the Other Side in an enormous bed in the Righton Luxury Beach Hotel!!! 

We are here because Haggy Aggy saw it on T.V. "Everyone deserves a lot of luxury once in their lives, RB," she said. "And witches and their familiars are no exception. Now lets get packing and go!"

We did not leave for TWO WHOLE DAYS because she couldn't decide what to pack.

This book is not in the library but you can get it in the bookshop in An Phu Supermarket. 

There is a series which you can buy too.