Can a teacher request for you to be sectioned, or tell someone if they're worried that you'll kill yourselves

I feel like opening up to some one. Me and my teacher have a good relationship. She knows I've been struggling with depression, I was going to tell her I don't feel safe, I don't feel like I can trust myself which makes life scary because I never feel safe. I make all these plans to overdose, Jump of cliffs, jump infrint of a train. I just want it to end. 
I don't know if she'll have to pass it on. I'm 18. 
I told her before when she asked if I had made plans that I had because I had and she didn't say anything. Idk, I just feel I want someone to talk to, I don't really care if she does pass it on, I'm just wondering if she can request for me to be sectioned, because I know family members can. Or request for an assesment. 
I just want to die like all the time. 

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