Well, be prepared that they will write down any part of your conversations with them, which could be used out of context, although for the children with disabilities, this is not such a big deal as child protection, I imagine! (I accessed DD's records and read all SWs' typed notes)
However, ime generally social workers wanted what was in DD's best interests, far more than anybody in the SEN division ever did - the trouble was that social workers don't have any sway over say the head of SEN!
Once DD was old enough to speak for herself, she could complain directly to the social workers about things happening at school she did not like. She had been bullied for a year by a boy at school (it was a residential school and he lived in our county, so they travelled to school in a taxi together, were in the same year group, and lived in the same house). We had complained to the school and got nowhere, because all they ever said was that they would talk to him.
One holiday, DD complained to the SW, he had hit her - the SW wrote to the school to tell them to convene a meeting with us, get it sorted out and send her the minutes! That was the end of the problem for DD!
Another time, DD complained the school was not letting her sleep after seizures and she was tired all the time. The SW told the school to let her go back to the house to sleep, if she needed to - and her TA did take her back to the house and watch over her, after that!