I live on Central Coast and grow lettuce through late autumn to late winter. I raise them in seed trays or scatter them in the garden as soon as the last really hot day has gone by and temperatures are no more than 35 degrees c or below. When I put them straight in the garden I scatter seeds over small area and cover with seed raising mix. I keep them moist with a gentle watering can. When 5cm tall I trans-plant them in to another bed. You could also use this method in flat seed raising trays and a spray bottle. By using sugar cane mulch in the ground surrounding the plants (not touching their stems!) I keep them moist. I also water every to every second day as the weather cools down. My suggestions would be scatter lightly oven baked ground eggshells or hair clippings around the plants to deter snails. if they become a problem. Grow with sweet peas and rocket for great salads. The peas will add nitrogen that the leafy greens will enjoy. Choose a loose head variety so you can pick it as it grows and get multiple harvests the size you want. also better suited to Australia. If you want to try planting lettuce now some tips to stop it bolting are to give it PLENTY of shade, keep harvesting it regularly, (about every second day once it gets going) keep moist (planter boxes might work but could be expensive) and pinch off buds that start to form. In my experience even a resistant variety in a nice shady place with lots of water will go to seed/taste bitter early if planted later than August. But I have seen it done. lettuce is a great to grow easy and rewarding but I would suggest waiting until after Summer. I plant lettuces April on, when you plan depends on your climate conditions. Try companion planting basil and tomatoes together while you wait or growing zucchini plants. If you have a meter square garden bed try planting 16 corn plants, 3 pumpkin or zucchini and once corn is 15 cm high planting a bean seed at the base of each corn plant. Beans are also good for nitrogen that both the corn and beans will need. All of the above I recommend planting now if you are getting the feeling it is already summer. I am not sure if what i have written is relevant to more inland areas of NSW but hope it may be helpful. Good luck with your gardening!

- Ferran