To a CPL holder without any job, they ask basic questions like VOR, NDB, FM, AM, GPWS, GPS, SSR, TCAS etc etc.
There is nothing fixed and its totally on their mood what they want to ask.
Just study all the topics. You have cleared the written, it should not be difficult to study all of it.
Anyhow the guys are good there, they wont be expecting you to know all the airline operations. Normal stuff. However air nav orals is a bit tougher than Radio one.
Good luck.