SueBee, as Wilma suggests, please see a solicitor who specialises in family law asap. You get the first appointment free. You may find helpful advice on the Family Rights Group website.
If your grandchildren have been made the subject of an interim care order, the court will have appointed a Children's Guardian. A CG is the independent experienced social worker appointed by the court, their job is to provide independent sw reports and assessments. To do that, they should see the children and interview all the significant people. I'm told that because of pressure of work, CG's don't do the in-depth work they did in the past but nonetheless, their job includes appointing and instructing a solicitor to represent the children. If you see a solicitor they will understand the complicated procedures that most of us (thankfully) never have to make our way through. A good child care solicitor would make phone calls to the sw team's legal department and speak on your behalf.
I'm sorry that you feel in the dark, it is so stressful. The other things you could do would be to phone the sw daily, if no response, ask the person who answers the phone if you can speak to the sw's manager. As well as the Children's Guardian, your grandchildren will have someone called an independent reviewing officer. Their role includes making sure that the children's circumstances are reviewed regularly. You can phone and ask for the name of the IRO and then ask to speak to her/him. Their role includes discussing contact arrangements and asking which family members want to be assessed as permanent carers for the children.
I hope this information may be helpful and doesn't make you feel even more overwhelmed and ignored. The family courts do recognise the importance of grandparents but someone needs to make the Judge aware that you are jumping up and down and asking to be assessed. That's something the CG would see as important but I expect the sw also sees it as important. I am making no excuses for poor practice but I'm told that case loads are impossible to manage. Cuts and increasing care proceedings are the cause.