Thanks for the replies.
I haven't signed anything yet, and have also told them I won't be picking dd up when they call. They know my feelings on it, as that it does not work for her, and just makes going back to school harder. She has never fully refused to go to school, but we almost ended up like that until she was moved out of the class to work with an LSA and two boys for the last four weeks of term.
She got excluded, and was sent home early quite a lot last term, in fact most of her exclusions for last year was during the summer term, adding up to almost two weeks off in total.
She doesn't like coming home from school, but I think that that is down to her power seeking behaviours.
The reason often for the unpredictably is that the explosions are usually the cumulation of lots of little things. If levels of stress are high then it would take very little to set ds1 off e.g. getting a maths question wrong, losing a game, name-calling, etc. When his stress levels are low he can cope most of the time with these.
That is my dd completely. Maths is her strongest subject (all are very strong) but she can't accept getting anything wrong so will end up refusing to even try, and if she does try, gets it wrong, she explodes. Even if the rest of the group got it wrong, that wasn't good enough for her, she had to get it right. When she explodes, she will go one of two ways: take herself off an hide away for as long as she needs, or will hit, kick, run, bite, throw things, climb up what ever she can, try to get any reaction she can out of the staff, (apparently she is in complete control of her emotions, knows what she is doing because she does it with a smirk on her face). When this happens, that is when they want to send her home. They wanted me to go up there and calm her down which would work for a bit before she ended up being sent home, because within minutes she had exploded again.
SA was refused because the LEA hadn't received the required paperwork from the school, and that they expected that specialist teachers to have been in to work with her. In hindsight, I should have put on the form that the specialist teacher from behaviour support had been working with her, but I was told by the deputy head (who was covering for the Senco whilst she was off sick) that they weren't a specialist teacher.
Thanks again for all your help!