Rather what I should do next with the school. As they don't have clear guidance for parents what happens if you inform of a drug related incident that involves your child which is why my question to all and sundry was ' If you knew your child would get suspended if you informed would you still inform? If the majority here said no they wouldnt inform knowing their child would get suspended then I'd have cause to contact the school and ask them to add to their drugs policy and if that happened ask them to remove the suspension on my sons record. Because of his suspension I feel guilty. Can't help that.
This is what it comes down to - your guilt.
You should do nothing about the school - the schools drugs policy is in place for if the information is brought ot their attention or they are caught, whether that's via a student, a parent, a member of staff or member of public. They don't need to stipulate every angle in which this information could be given to them, they only need to stipulate what would happen if it was brought to light.
You brought it to light, and they acted accordingly.
It baffles me slightly that you went into school, knowing the school has a drugs policy - and expected the school to just waiver him of any consequences. For starter - you (his mum) told the school. Not himself, so he can't exactly be seen as being plagued with guilt over his actions, if anything it seem's like a pissed off mother who wants their son to learn the value of consquences.
Your pushing this angle because you feel guilty for essentially getting your son into trouble - but the school should not waiver their rules for you.
Its like walking into a police station and saying 'my son stabbed someone, but I just told you about it so he shouldn't get into trouble right?' - it doesnt work like that. He broke a rule, he got suspended.
The only thing to do is move on from this, the school acted accordingly.