Warrumbungles might be a bit hot in January, but is a great area - very scenic, with some great walks to do.
Camp Blackman is the main camp ground in the National Park. We were last there in 2009. It does have powered sites, as well as unpowered, over quite a large area. There was a powered area laid out like a conventional caravan park area, but further along was the older section, spread out along a creek. This was more informal - just several clearings with a few power poles and taps - plenty of space whether you wanted to hook into power or not. The one amenities block served the whole area - very modern, solar heated showers, coin operated. There was also one (more?) long drop toilets at different locations.
You have to pay the National Parks entry fee and a camp fee on top of that. Because we were there for a while, it was economic to buy an annual country Parks Pass ($45 from memory) and save having to pay the park entry fee.
I will try photo resizing and see if I can post a pic.

thank you, much appreciated.