Site visited in March 2018, both designated components. As Frederik described Tyrendarra area I would focus mainly on Budj Bim - Mt Eccles National Park.

To get there you will probably need your own car as there are no public transportation in the area. The best place to start the visit is a parking near Lake Surprise (coordinates - 38°03'30.8"S 141°55'21.5"E). It is also a camping area with a small visitors centre with basic information about the place. Lake Surprise is a crater lake where former volcanic activity is still visible. There are 2 hiking paths around the lake the one just near the lake (allow at least one hour for the loop) and the second  that goes on the crater rim (2 hours). The area is quite spectacular although there is not much to see in terms of ancient human activity.

From that point you can also visit lava blisters and natural volcanic caves. One of them is called Natural Bridge and is located some 45 min from the visitors center. there is a direct hiking path and unsealed road. Coordinates of the place: 38°04'12.5"S 141°55'09.0"E.

If you wish to see the Tyrendarra area from Mt Eccles it is necessary to go around (via Bessiebelle to the East or using Ettrick-Condah Road to the West) 

Official visitors guide with a descent map of the area: 

http://parkweb.vic.gov.au/__data/assets/pdf_file/0004/315607/Mt_Eccles_NP_parknote.pdf