Compatibility summary
You will need a travel adapter in Czech Republic; plug types used there differ from Australia.
Plug comparison
Australia plug types: I
Czech Republic plug types: C E
There is no common plug type between Australia (I) and Czech Republic (C E). You need a travel adapter.
Voltage comparison
Australia: 230V, 50Hz
Czech Republic: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.