Do I have to have a hair test for alcohol ordered by CAFCASS at family court last week? Lies told by ex but they believed her.

I had children regularly until I met new lady. Since then ex has stopped contact saying I drink even though she was happy for the last 2 years for me to have them and to let them stay overnight. I do drink socially but not when I had the children. Do you think I need a solicitor for next court appearance end June? Cafcass seem to believe her lies even with no proof.