You are not doing yourself any favours here. I was very much on your side before, but now I feel like you are just being vindictive.
Head of year being openly bisexual? How is this any worse than anyone being openly straight? Or being openly married, or openly single? As many teachers are, simply by being Miss, or Mrs, or wearing a wedding ring. How helpful to other LGB children to have role models of people being open about their sexuality.
Teacher on phone all lesson? How do you know what was going on? Might very well be teacher trying to deal with IT outage that was preventing him/her access to the lesson they had set up _ I've been in this position many times, school IT can be crap, but we still are required to set lessons up on it. Maybe it wasn't even a teacher, but someone who had other urgent work they needed to be getting on with, but agreed to do it in a maths lesson so that the class did not need to be sent home for lack of teacher - I have been in that position too. Maybe the teacher was dealing with an emergency hospital consultation and a phone consultation can come at any time in the day, and you might have to drop everything and be available to fill forms in and answer questions. I was informed I had cancer during a year 7 lesson, but carried on, and was told to fill in immediately required forms during a year 9 lesson, and would have lost the operation slot if I hadn't. Would you have preferred I took the whole day off to wait for phone calls at home, leaving all my classes without a teacher?
Kids walking around the playground during a PE lesson - well, it depends on the supply teacher, doesn't it. If they are not PE trained, then they would not be insured to allow children to run.
A boy being allowed to wear a skirt? Who is that hurting? presumably girls are allowed to wear trousers. It is normal for either sex to be allowed to wear either uniform, in fact it is likely to be illegal to prevent it
A boy throwing a chair at a teacher but not being disciplined? You have no idea ho that was dealt with, or what the consequences are. It would break GDPR rules to tell you, or your grand daughter.
You seem to have no idea of the problems schools face, and how they have to deal with them. Most schools are chronically under staffed, and most of these situations arise from simply not having enough teachers. Many of these things are going on in many schools all around the country. If you have any suggestions of how to do better, with such a shortage of teachers, I would like to hear them