Easter is holiday time and many restaurants close. Do you know where you are staying or which restaurant you are considering?
You will findthat very few pubs/shops/restaurants will be open on Good Friday so which day of Easter do you usually have your "big meal"?
As said above... religious traditions are not high on the priority list of many Aussies... South Australia in particular was a state founded on Religious Freedom and we have long-standing associations with many religions. Interestingly enough though, whilst we are the "City of Churches", a great percentage of our population seem to hardly be religious at all.
Some families observe Easter traditions but many S.Australians use the four day break to escape the city and head to the wine regions, beach or up the River with family and friends.
Depending on your accommodation and the day you usually observe your tradition it may be even be an option to cook up your own "Barossa Easter Feast"