NB: She writes a LOT of fantasy steampunk, all set in the same universe and often sharing characters—including "Emmeline's Empire" (Emmeline Muchamore is the heroine of the Antipodean Queen Trilogy). You can attempt to decide on the best reading order by looking at the full list: felicitybanks.wordpress.com/2017/10/02/all-steampunk/
2. The Heest Trilogy is a pirate fantasy trilogy (already written and in the publication pipeline) for ages 10-14 (or people who aren't prejudiced against books that are welcoming to younger readers). It's set in the world of Rahana, which is by no means restricted to three novels. felicitybanks.wordpress.com/2018/01/04/heest-1-the-monster-apprentice/ Rahana is basically Narnia, with pirates.
The Monster Apprentice - out now.
The Princess and the Pirate - out Februaryish 2019