The Worst Witch by Jill Murphy

Catch up on Mildred Hubble’s magical adventures at Miss Cackle’s Academy for Witches with these reissued editions featuring energetic new covers. Mildred Hubble is starting her first year at Miss Cackle’s Academy for Witches — and making a mess of it! She can’t ride her broomstick without crashing, she’s always getting her spells mixed up, and worst of all, the teacher’s pet, Ethel, has just become her sworn enemy.

Ah nostalgia; loved these as a kid

A 1001 CBYMRBYGU. At Miss Cackle's Academy for Witches, there are many witches, but no one is as terrible at witchcraft than Mildred. She goofs up every spell she attempts. Poor Mildred is always in trouble.

...the girls marched up in single file to receive their kittens. Mildred was the last of all, and when she reached the table Miss Cackle pulled out of the basket not a sleek black kitten like all the others but a little tabby with white paws and the sort of fur that looked as if it had been out all night in a gale.

“We ran out of black ones,” explained Miss Cackle with a pleasant grin.

Miss Hardbroom smiled too, but nastily.