Most primaries are good.
If there is violence it'll be a child with additional needs not coping. This can have a big impact on a class but is largely the luck of the draw - there aren't enough spaces for children with needs at special schools and so many start in mainstream before collecting the years of evidence they need to get the support they need.
Secondaries are a different story. In some areas they are rural and there is basically one choice and everyone goes there. Because children are grouped by ability the experience they have is very different depending on if they are in top ability groups or bottom ability groups. The top ability groups generally have little to no disruption and no violence. The bottom ability groups are a mixture of incredibly well behaved kids with Learning disabilities and kids who have major mental health/trauma issues and are violent.
Some secondaries split the bottom groups out into a learning difficulties group (I used to specialise in teaching these groups) and a mh/trauma group because the two groups largely hate each other.
In towns where there is a choice of secondaries you tend to find that there are schools seen as "good" and schools seen as less good.
The schools seen as "good" take kids from their catchment area (so will have the kids with learning disabilities and the mh/trauma kids) but in addition are oversubscribed as people from other areas want to get their kids in there.
In general children with mh issues /trauma are much much more common in poorer areas. This means that schools in those areas are fighting hard just to get the kids into school, with clean uniform and ideally ready to learn. It's hard for kids to do that if, to take one example from my school, parents are fighting a nasty divorce, dad initially refused to see kids but then mum lost job and turned to drink and now the kids are placed with dad by SS but are very aware he doesn't want them.
Actual proper violence in secondaries is quite rare. Pushing and shoving and he said/she said is very common. However it tends to be the same children all the time (usually either mh/trauma or a group of year 10 lads who think they are in a wildlife documentary about who leads the pack) and so it's really easy to avoid.