The Bulldog Breed (movie, 1960)

Norman Puckle (Norman Wisdom), a well-meaning but clumsy grocer's assistant, can't seem to do anything right. After being rejected by Marlene, the love of his life, he attempts suicide, but can't even do that. He is saved from jumping off a cliff at 'Lover's Leap' by a Royal Navy petty officer. He persuades Puckle to join the Royal Navy, where he'll meet 'lots of girls'. Life in the Navy proves not to be as rosy as it's been described, and Puckle fails at every task during basic training. But despite this, he's regarded by the Admiral in charge of a rocket project to be a 'typical average British sailor', and chosen to be the first man to fly into outer space in an experimental rocket.