Regarding school, I found it immensely helpful as it gave my days a focus. My situation was different as it was home that was the problem but if pastoral care can be given a brief and if she can be taught how to calm herself down or excuse herself (with a pass) if she feels a bit wobbly, there's no reason she couldn't go.
No problem OP, I'm glad to help- baby just gone to sleep so I can write proper replies!
Grounding techniques are the number one most important thing for daily life as someone with cptsd, in my opinion...
The basic principles are that they keep you grounded in the present, rather than floating off and getting muddled up about whether the stuff that happened then is happening now or if the now is really real.
So, anything that makes 'now' more solid. Try ticking off the senses. What can you hear right now? What can you smell? What can you feel on your skin- a scratchy jumper, or the floor under your feet?
Observing objects. Pick up the thing nearest to you (first of all that brings you back a bit as you are moving, which gives you control.) List 5 things about it. Eg, this is a pencil. It is red. It has an eraser on the end. The lead is slightly broken.
Taste something (especially as taste can be a trigger). Put a grape in your mouth. Feel the round skin. Then bite it. Feel the skin break under your teeth. Focus on the sharpness of the juice.
Smell. Smell is a huge trigger for me so I always carry a little thing of solid perfume, if I'm feeling a bit off I just sniff the perfume. Focus completely on that smell, nothing else.
If you have nothing else, look at your hands. Stretch your fingers. Move them one by one. Look at your nails. Are they chipped? Your knuckles. Watch them move.
And breathe. I find breathing the hardest but some people find it helps to focus on breathing rhythmically.
Then, when calm, I like to think back to note what the trigger was- someone sitting too close, a song playing, whatever it might be. And then right down what it triggered, so it's out of my head and on paper.