It's become worse over the years. (I taught in Scotland from '84 until last year.)
In 2001, one of my teaching colleagues was punched in the stomach by a 15 yr old thug. He blocked the second punch.
The very respectable parents tried to have my colleague arrested. When the police said that there was no case to answer, they complained to the Director of Education and had my colleague doorstepped by a tabloid.
He was suspended pending an investigation and reinstated but eventually resigned because the boys at the school were targeting him.
No, the police didn't charge the pupil. At that time in Scotland, the Children's Panel dealt with under-16 crime and the police often didn't bother to pass details on since it wouldn't normally go to court.
Later, I was punched in the stomach by a boy from the same age group. The police 'lost the statements' and the boy's friends tarnished my name by saying that I was a homophobe. I didn't even know the kid until the day he ran into my room after another boy and then punched me in the stomach while I tried to phone for back-up. (I had been pregnant—though I wasn't showing—and was trying to protect my stomach by staying out of his reach, which was why I hadn't physically intervened.)
The only consequence was that, in spite of the 'lost statements', the police referred the boy to SACRO who then phoned me to explain that I'd 'got in the way' of a homophobic assault and that the boy wanted to meet me to apologise. I refused.
It was after that that some of his pals started to spread the homophobe rumour. It didn't stick, but it could have caused me a great deal of damage.
In my last year of teaching, a young woman teacher was punched in the arm. She was scolded by management because she asked for the culprit to be removed from class for a week. On the same day, a heavily pregnant Pupil Support Assistant was punched whilst walking down a corridor. Fortunately, her baby was okay.
Sentencing guidelines up here now mean that it is highly unlikely that anyone under the age of 25 will receive a stiff sentence and teenagers know that they're practically fireproof if they're under 16.