I read a YA book 13-14 years ago about a fantasy world where everyone is magically connected to a small animal, like a rabbit or dog. The kids are maybe 11 or 12, and can communicate telepathically with their animals. They can never get more than a few feet from them, or they start feeling awful. Any idea what book this is? I'm pretty sure the author was British.
Perhaps Northern Lights by Philip Pullman, who is indeed British. Also known as The Golden Compass in the USA.
The novel is set in a world dominated by a theocratic international organisation, the Magisterium (also commonly called "the Church"), which actively suppresses heresy. In this world, humans' individual souls naturally exist outside of their bodies in the form of sentient "dæmons": animals that constantly accompany, aid, and comfort their humans. Children's dæmons can freely and instantaneously change their appearance into that of any creature, extant or imagined; once they reach puberty, however, all people's dæmons settle into one permanent form.