Ok, let's be clear as to what has happened here. BigChocFrenzy is very wide of the mark in asserting that the judge did not require him to agree to medical treatment. The judge did indeed impose a medical treatment requirement. Some of the other posts are also incorrect.
As some have pointed out this is legally a custodial sentence. He has been sentenced to one year in jail. However he is not going to jail immediately as the sentence has been suspended for one year.
In addition to this he has been sentenced to 100 hours community service, put on probation and subjected to a restraining order.
The suspended sentence order also includes a requirement that he undertakes treatment for his paranoid schizophrenia. If he fails to do so he will go back to court for sentencing which is likely to mean going to jail.
Given the information available I think the judge regarded this as a Category 2 ABH offence. Given his mental disorder, the fact he was acting alone and the lack of any weapon (as far as I can tell from the press reports) that seems about right. Under the sentencing guidelines a Category 2 offence has a sentencing range of low level community order to 51 weeks in custody so the actual sentence is right at the top of the available range. For a Category 2 offence the guidelines suggest a strong presumption in favour of a suspended sentence if a custodial sentence is passed.
It is possible the judge regarded this as a Category 1 offence but positioned it towards the bottom of the sentencing range due to his mental disorder, lack of any weapon, etc. That would result in the same sentence but it is less likely the custodial element would be suspended.
One can, of course, argue that the current sentencing guidelines are wrong. However, given the current guidelines the sentence does not immediately appear to be unduly lenient based on the information in the press. The prosecution, of course, know what evidence was presented in court so are well placed to judge whether the sentence is unduly lenient and hence whether to appeal.
I wonder if it would have resulted in a custodial sentence if the victim had been a middle-class white teacher from the school, or the head teacher, rather than 'just' a TA who is also a local parent....
He has got a custodial sentence. However, I'll take your comment as wondering if he would have gone to jail immediately rather than face a suspended sentence.
The judge must follow the sentencing guidelines unless there is very strong justification for stepping outside them. If the judge goes outside the sentencing guidelines without adequate justification the sentence will be overturned on appeal. If the facts are the same the outcome should be the same regardless of the identity of the victim. If the attack was racially motivated then yes, the sentence would have been higher and he may have faced immediate custody. But if there was no evidence of racial motivation I would still expect to see a suspended sentence.