Indeterminate greenhouse tomatoes or parthenocarpic cucumbers (Lebanese types) can succeed during the late spring, to early fall. This is when the light levels are strong enough that even indirect light is enough. Squash not so much. If you could get some of the winter varieties grown in the greenhouses in southern Spain, maybe.
All of the leafy greens are possible year round - lettuce, spinach, kale, etc.
For some permanent greenery houseplants are an excellent choice. Ferns, african violets, mosteras, philodendrons, kalanchoe, etc would all do well in that spot. Sydney very rarely frosts so you have a wide choice to choose from. Pretty much everything will work. For watering make sure you good drainage on the pots on only water they are dry.














I use the agricultural suppliers for most of the basics: compost, potting mix, fertilizer etc. If you can store the larger quanties it is much cheaper. The last 1,000lbs of compost was $80.
For little things like pots etc, shop around. They sometimes are at places you wouldn’t expect. The best pots are not at the nursery but at a local home decor place. I got some nice ones a few years ago at my local grocery store.
The best seedling flats are at the hydroponic store where the clerks have red eyes…