Knott was sentenced after a court heard how drink and drugs had quickly changed his behaviour from being a “Mummy’s boy”.
The 20-year-old pleaded guilty to assault occasioning actual bodily harm to Hannah Adjali, assaulting Clare Lancaster and criminal damage to an iPhone. He also admitted breaching a suspended sentence order.
Prosecutor Paul Brown told Peterborough Magistrates’ Court on Monday that Mrs Lancaster was at work when she was alerted by a neighbour to a disturbance at her home.
“She was told her son and girlfriend were arguing and she should return home immediately,” added Mr Brown.
The court was told of a series of incidents between 7pm and 8.30pm including Knott and Miss Adjali slapping and punching each other, Knott grabbing his mother by the scruff of the neck and throwing her phone on the floor twice.
His mother locked herself in the bathroom for safety.
Miss Adjali suffered black eyes, a split lip and swelling to other parts of her face.
Mrs Lancaster told police that her son had been “very much a Mummy’s boy” but the past six to 12 months had been very difficult due to his misuse of alcohol and drugs.
Solicitor Simon Rice told the court that Knott had told him: “I regret this, I’m expecting jail.”
“He had been working for two-and-a-half years but this time last year he lost his job and turned to alcohol and drugs,” added Mr Rice.
He said Knott, of Damson Way, Lower Cambourne, had “completely lost his temper” during the row with his girlfriend last Saturday.
The District Judge told the defendant: “This has occurred within the matter of just a few weeks of you being made the subject of a suspended sentence order.”
Knott was given 12 weeks’ custody for the ABH to run consecutively with the activation of the four-week suspended sentence.
There was no separate penalty for the assault on his mother or the phone damage. He was ordered to pay £128 victim surcharge.