Hi Renee,
I was in the same situation when we moved here. I live in Mitchells Flat which is near singleton and we have a local playgroup here but it would take you 20 minutes to get here.

Found some information for you.

Playgroup Name: Cessnock Education
Location: North End Hall
Address: Church Street Town: CESSNOCK Postcode: 2325
Phone: 4991 3277 4991 3271 Email: missjulie@hotmail.com.au
Website:
Day: Wednesday Time: 09:30 Type: General

Good luck