No. Slow worms (Anguis fragilis) are legless lizards, not snakes, and they are harmless to people. Britain’s Natural History Museum notes that they seldom bite and can be handled gently without danger if you need to move one.
They are often mistaken for snakes in gardens and allotments, but they have eyelids, a slightly notched tongue, and no venom. Handling them unnecessarily can stress them into shedding their tails, so leave them alone when you can.
Source: Natural History Museum – Slow worms: Britain’s most unusual lizards.