What is the title of 10th Georgia Nicholson book?

There is no 10th book in the Georgia Nicholson series. The series, written by Louise Rennison, has 8 books:

1. Angus, Thongs and Full-Frontal Snogging

2. On the Bright Side, I'm Now a Virgin

3. The Secret Diary of a Teenage Girl, As It Happens

4. The Confessions of Georgia Nicholson

5. It's OK, I'm a Girl

6. The Worst Thing About My Life

7. Not My Problem

8. Just My Luck

There are also two books focusing on Georgia's younger sister, Robbie:

1. Robbie's World

2. Robbie's Secret