Cafcass workers do not meet all children because sometimes families can sort things out on their own. If the court has asked Cafcass to produce a report, a Cafcass worker will nearly always talk to your child (depending on their age and understanding) about their wishes and feelings and what they would like to happen.
The Cafcass worker will not ask your child to make a decision or choose between you and the other parent. The Cafcass worker will usually talk to your child alone.
There is more information on the Cafcass website.