Hedgehog

Omnivorous mammal, the only British mammal to have spines.
Nocturnal and eats invertebrates, frogs, birds eggs.
They hibernate in winter, constructing strong nests called hibernacula.
They curl up as depicted when threatened, using their spines for protection.
Interesting behavioural 'quirk' is self annointing - they will cover their spines in frothy spittle when encountering a new taste. (shown in the second photo)