Hi Craggy ..... the Aldi detector is probably better suited to searching for coins and relics in parks or at the beach.
It MAY, but only may, find gold in old mullock heaps but finding some that haven't been detected with for want of a better word "better" detectors.
If you want to get into detecting try getting your dad to hire a unit (Ballast/Maryborough) to see how you both like it before going out and spending more.
They are reasonably cheap to hire for a day/weekend.
Good luck, Tom