Georgie Smibert

When Carlton Layton arrives home to find his wife in the arms of another man, he dons the outfit he wears as a children's entertainer and slaughters them both, fleeing into the night. Five years later, Carley Lewis is asked to babysit on Halloween night whilst the child's parents go out to a party. But someone wants the child. Someone we know only as 'the Cleaver'. (amazon)

Years after WW3, scattered individuals and gangs survive by plundering, killing, cannibalism etc. A young man tries to survive on his own in rural "England". (imdb)