This is a book in the Horrible history Dead Famous series. Boudica is a warrior queen, a British Jhansi ki Rani, who defied the Roman rulers of her time.
 
Note about the Horrible History series. These are absolutely wonderful, fun (a little gory though), history books for the 9 - 12 year old range. Try one and see if your child likes the format. You may find that they will be hungry for the rest of the set after they are done. Depends on the kid though, some kids won't like it. This is one of the books that is perfect for getting from the library: you can check it out and see if it works for your child before investing money, if you want to buy the series.