Welcome to the forum, Sparra. Nice to see another local in here!
Turbo timers aren't essential as long as you remember to give the turbo time to cool down before you shut the engine down.
If you're above 2,000rpm as you approach your home, your turbo is spooled up and it's hot. If you can cruise in and not get up into boost range, the turbo will be cooling itself off naturally and you can forget getting a turbo timer.
However if you have to drive it in boost range (eg uphill) and want to shut down fairly quickly, a turbo timer would be beneficial.
For those that don't know why: if the turbo is spooled up (spinning hard) it is highly dependent on the oil in the bearings. This oil is delivered by a tube that comes up from the engine and is returned to the engine by another tube. The heat of combustion is delivered directly to the turbine half of the turbocharger - it can sit up at around 650C or more at this point. If the turbo is still spinning and still hot when the engine is turned off, that essential flow of oil is stopped. This causes the oil left in the bearings to cook rather rapidly. Even the best oils with the best anti-varnish agents are going to suffer in the repeated presence of that much heat.
Which turbo timer should you get, if you need one? The ONLY one to consider is one that monitors the temperature at or near the turbo ("EGT"). This allows for shorter on-times if the turbo is only just over temp, or longer ones if it's way over temp on a hot day.
As far as I know, turbo timers are not legal in Australia - but as with many, many other things you can do to your vehicle, if you're not being an idiot with your car and drawing attention to yourself, it's unlikely that you'll ever have any grief over it.