The electoral roll is simply made up of legal names and addresses in each electorate.

Your name must be on the roll, or you can't vote. So fake names wont work. Nor will a name without the correct address.

If you turn up and your name/address combo is already crossed out, you will be given some sort of provisional ballot, while an investigation is started.

It would be trivial to learn someones address and turn up at a booth in their electorate early to vote in their name, but the irregularity would be obvious.

Also, it is very difficult to stay off the electoral roll or have an incorrect address, because most interactions with a government agency will automatically update it. ie: get or change drivers license details or get a passport, or enroll you kids in school etc.

You may be purged from the roll if another person legitimately enrolls at an address you used to be enrolled at, but this will be picked up quickly in practice when you change your address for any official paperwork.