Joining this thread to add my misgivings about how secondary works out for children with ASD.
My experience so far this term with ds2, who has a diagnosis of ASD, no EHCP, and in mainstream secondary - not great.
His primary SENCO last year apparently visited his secondary to liaise with the SENCO there so that things could be put in place for him starting in September.
I heard nothing from SENCO at new school at all since registering ds.
Three weeks into term DS gets his first detention for arguing with his class tutor. Tutor phones DH sounding seriously pissed off that DS was difficult. DH says 'by way of explanation of some of his challenging behaviour, you are aware that he has autism aren't you?', to which the tutor responded 'Umm, no, I haven't looked at his file'. 
So this is the tutor who he sees daily, who is responsible for communicating with the staff who are teaching DS. I'm now assuming none of the other people who teach him are aware of his diagnosis.
DS has been getting more and more anxious as the term has continued. After a fortnight he was sobbing every morning, begging not to go in, unable to eat his breakfast, complaining of stomach pain. Three boys started picking on him in his class, and one threatened to smash his face in with a rock. Another boy told him in PE that his breath stank (it doesn't - I ask him to breathe in my face to make sure he's brushed his teeth before he goes) and then got all his friends to join in laughing at him. So the bullying begins. He's never been picked on in this way before, and had plenty of friends in primary (which was a big fairly rough inner London primary).
Anyway, I contacted the HOL for year 7 and she asked us to come in and talk to her. He is now on the radar of the KS2 learning mentor, knows where to go if he's overwhelmed, and the bullies have been spoken to. He came back from school on Thursday and Friday much happier.
But as far as his needs go, I have no confidence that his teachers will really understand him or be able to properly accommodate him because they simply DON'T HAVE TIME to do all the research and preparation they would need to do to really put all the necessary things in place, and he has no allocated, paid for one to one support. There are 360 children in his year group this year, which is a bulge year, and I feel like his teachers are working at the limits of their capabilities. There are a good number of quite disruptive children at the school and it's also an environment where there are many children from academically ambitious families. This puts huge amounts of pressure on teachers and I just feel, being realistic, it's going to be very hard for them to give him the one to one support he needs.
Anyway, the long and short of it is that I'm going to write a letter for each and every teacher on his timetable setting out the basic things they need to know about him and his diagnosis and what strategies have worked for him in the past to help him in the classroom. I'm going to hand deliver them to the school. I'm also asking for copies of everything which is in his file at schooland will deliver my own file of information (containing things like copies of his old IEP's, the EP report and the CAMHS report) to the SENCO to fill in any gaps. The school isn't a terrible one, but they are a bit crap with paperwork and organisation so I think it's useful for me to step up on this front as soon as possible.
If DS continues unhappy, and there are bullying issues that aren't resolved, or he's not making progress, I'll pull him out and home ed him.