I think LAs deal with TAs very differently.
A neighbouring county has a peri TA mentor, specific TA CPD, TA support services... you name it, they've got it.
10 miles down the road, our county has nothing - zilch. We have to train all TAs in-house, and usually use our own teachers to do the training (although they do attend some whole school training sessions and insets). I think being a TA in a school like mine is a massive challenge and admire them for their patience and resilience.
i have a statemented child at the moment. His TA is 1:1 all the time - very tiring for a start. This statemented child has no external agency support at all, so the TA is expected to deal with all his language, OT, social and attention problems. We were advised to download a SALT document to help her. It's a ridiculous demand to make on an untrained person, and we're just about muddling through together.