Marne Ventura 
Nervous Nellie Fights First-day Frenzy [PDF ebook] 

Nellie is nervous about her first day in year five. She expected to be in the same class as her three best friends, as she had been since nursery. When she finds out that she will be in a class without her friends, and a teacher who is new to the school, she gets very worried. Call in the Worry Warriors–those three best friends–to help her through it.