Though this is not a book but Therethere is an American YouTuber that's living in Croatia and often she often makes videos about her life there in Croatian: https://www.youtube.com/channel/UC_k8snbkwzqpxSIq5DUZYbwKaleigh Hendershot - This Croatian Life.
I would suggest you to watch cartoons like Peppa pig, just to get a "feeling" of how it sounds