I don't know where people think that the law doesn't allow them to protect themselves, their family, or their property, because it does.
Under British criminal law, a person is allowed to use "reasonable force" to either arrest or stop a person commiting a criminal act, in self defense, or defence of property.
Obvioulsy the key point is "reasonable force" and is up for question, but you are protected under British law, and should never think you aren't.