Partners history of DV affecting my unborn child

[UpsetMumToBe]

Myself and my partner have been together for 18 months and i am currently 35 weeks pregnant. I have recently been contacted by a SW to inform me they are going to conduct an assessment due to concerns raised for myself and my unborn child. Although they will not tell me what these concerns are at present.
I am aware that they were raised via a cafcas officer during a current court proceeding in relation to my partners child with his ex.
These concerns stem from my partners previous relationship with the mother of his child and history of DV in the form of harassment. This was surrounding parental access as my partner was denied access to his child by his ex after they separated, so would continuously contact her in order to try and see the child. No reports of any physical violence had been made. He currently see’s his child through supervised contact as a result of this. I feel i need to add my partner has always been 100% transparent with me with regards to his offences.

There is absolutely no DV within our relationship and never has been, and i have absolutely no concerns surrounding my partner in relation to his parenting. We get on so well that there is never so much as a raised voice in our home and NEVER any arguments. We both work full time, have good careers and have a great support network of family and friends. My partner absolutely worships me - i strongly believe he would never harm me or our child in any form. The relationship he has with his current daughter reflects this.
What am i to expect when the sw attends my home to commence their assessment?
My concern is that they will try and separate us in order to prevent my unborn child being exposed to any future domestic violence but i fear this will be the worst outcome for all of us. Especially with it potentially happening whilst i am post-partum. Will having my mum live with us whilst they conduct the investigation help reassure my childs safety? Should i seek legal advice now or should i wait until they meet with me?