Without wishing to make you look over your shoulder, Britain's only poisonous snake is waking up in early spring too! But don't worry, Adders very rarely attack and, being cold blooded, are far too busy trying to warm up in the British spring, which is a task in itself of course. Couple being cold blooded with not being fussy with their food, and they're extremely well suited to the hibernation lifestyle. They'll have a go at anything from mice, voles, birds, insects, eggs and frogs. Just to put your mind at ease, it's very unlikely you'll find an Adder in a built up area as generally, they're found in moors and grasslands so you can come down off from standing on that table.