KeepOn, I would open of course absolutely wait until he came home from school and open it together.
Seriously though, I'd need to read it first to prepare myself for his reaction.
Your plan sounds like a good one for some dcs. It wouldn't work with ds1 unfortunately, as he would need me to help him handle the emotional fall-out - given that his school can't even meet his basic needs, let alone deal with his anxiety and poor emotional literacy.
I have had ds at the GPs again this morning. He's coughing to the point of being unable to breath, sleeping deeply (which isn't at all like him) yet exhausted, an odd pale green colour with red-rimmed eyes, is running to the toilet literally 4-5 times an hour and keeps asking me why everything looks and feels strange. 
GP says chest is all clear, has upped his asthma meds sightly, but both he and we are pretty sure it's all anxiety/stress related and that a good dollop of that is to do with all this secondary transfer stuff. Doctor said he is very concerned about him and thinks he/we need to keep a close eye on him. He's back there again next Friday for a follow up.
Despite all this, no-one will refer him to CAMHS, as they won't see him - because it's school related.
Paed bounced it back to EP, who said all she can offer is to come and have a chat with me about 'mindfulness' and relaxation. My Mum is a psychologist, specialising in transpersonal therapy - her little finger knows more about mindfulness than the blooming EP will ever know.
Yes, it's school related anxiety, because we manage things to keep his anxiety under control at home and he is secure and happy here, so because we are good at supporting our son and school isn't they won't help, because his stress and anxiety is only school related. Apparently, if the source of the problem, (ie school failing to implement statement - plus - the LA and Academy screwing up secondary transition) was removed he would no longer be anxious, therefore it's not classed as a MH issue. 