I like "Living with a Houserabbit" by Dykes and Flack, the only thing is though that in the accommodation section there are pictures of rabbits in small hutches and runs, but the other sections are all really useful I find.
I dont know if that would be suitable for primary school children though.
Its not a Rabbit Care book so dont know how relevant this would be but "Rabbits - Gentle Hearts, Valiant Spirits" is a lovely collection of real rescue rabbit tales, and at the end of each story is a little info box "About Rabbits". There is a short rabbit care section at the back, but I imagine its not quite what you are after. Sorry!