Rejected petition Mental Health and the Schooling

Mental Health Awareness is being increasingly pressed upon schools, but I feel that there is a much larger issue being overlooked.
Telling a crowd of year 8s that self harm is a serious matter is barely helping, if at all, with the matter. Adults in a more senior position, such as a Head of Year, Pastoral Support Worker or Deputy Head, should have to know more about mental illnesses and also where and how to give certain exemptions to a student with such misfortunes.
For example, a suicidal student with insomnia, severe depression and anxiety should not be expected to have the same attendance, concentration span and punctuality in school as a perfectly mentally-stable peer. It is also extremely unreasonable to punish someone in such a position in the same way as you would a normal underachiever who just cannot be bothered to move.
I would like it to be compulsory for a student in such a position, if they tell a teacher so, to be allowed to be excused from the normal school rules.