MTS, DD2 has been bullied at school. She came to me for help, which was forthcoming. (We discussed how she could act, so that she was not a "natural victim"; she also asked me to contact her form tutor about it in one occasion, but not on others, when she thought she could handle the situation, herself.)
I think that if a child is not supported, or for some reason, believes they will not be supported, then it could lead to very tragic results.
FWIW, DD has learnt a lot from these incidents. She has learnt there are things she can do herself. She has learnt that it is okay to ask for help. She has learnt to empathise with the bullies, to understand (although, not to excuse) their behaviour.
These situations have been good for her.
But, if I had not assisted her, and the school had not done its part, she would've learnt that bullies make your life miserable, and you are at their mercy.
We have no reason to believe that the OP's DD's school would not act as my DD's school did.