Eva Ibbotson is an English writer who has written two very pleasant fantasies, very similar to the style of Harry Potter (but written years before).
WHICH WITCH
Arriman the Awful (or not so very Awful) has to chose a bride in order to ensure the continuation of Evil and Darkness. But all the local witches are awful except poor Belladonna. She's unfortunately a light witch and would therefore make a most unsuitable bride for a dark wizard. However, with the help of an orphan named Terrance and a special earthworm named Rover, perhaps she come become dark...
THE SECRET OF PLATFORM 13
I'm not quite as familiar with this one, but it's more light, British-style fantasy with appealing characters that Harry Potter and Dudley strongly reminded me of.
