Plant Eucalpyts at your peril and have fun getting things to grow under them. Low maintenance? Northern Tassie yeah? Retaining wall across the front set back 1m from front boundary with a return either side(height? I don't know your levels but 1 to 1.2m is always a good height and needs no engineering detail). Scoria or white pepple, multi coloured stone between nature strip and base of wall. Above retaining wall a mass planting of succulents amongst another stone bed with some semi mature shrubs that grow well in your locality. Wide as you like it in regards to the garden bed above the wall with stepping stone(big paver, non invasive ground covers in confined squares ect) access to it and through it. One specimen tree in centre of garden(no...not a gumtree. Got a farm? Yes? Then you can plant a gumtree). Various really large pots with specimen plants in them placed up near your front entrance. A detailed plan could be done with much more info but you'll have to contact a local landscaper for that.(and plant advice and try to get an idea of where you plant/tree choices will be in 10 years even your not there) .

I share your exasperation! We have a large garden with clay soil at our place in sydney and limited budget to redo the whole thing! With 2 kids and work it's hard to keep the backyard looking good. I've found that lilli Pillis worked a treat for screening and grew quickly ie within 2 years were at fence height ( 50cm when planted ) though it looks like you have some hedges growing that may be these already? There are more tree like versions of lilli pillis eg waterhousia floribunda see picture - it's grown over 2 meters in 1.5 years now almost 4m tall and starting to throw shade. We lost a heap of shade when our large Blum gum was removed due to safety reasons. Another option might be a baby citro gum tree? For general landscaping I also love purple fountain grass another plant that really thrives in our climate. Gets to about 1.6m tall and looks very pretty when there is a breeze and they are nice and soft for kids. Agapanthus are another plant we cat seem to kill, and they flower all spring and summer. I often take a look and see what the council plants in the area, usually gives me an idea of what is likely to grow and not require excessive maintenance. There is a fair bit of trial and error some things that look great just can't cope with my low/zero maintenance strategy I now order plants from a wholesale nursery as retail prices can be a budget killer. Also IKEA have good freestanding umbrellas, works well and was cost effective, casts a large amount of shade and can be moved around the garden if needed. The lawn is a bit of maintenance but speaking from experience if you don't have to water it then mowing is probably easier than garden beds, I haven't yet found a way to really stop weeds, so that might be a consideration. Hope the tips are helpful.

@Anne we are drawing to the end of our similar area renovations, I am looking forward to getting the furniture out of storage and thinking what stays and what goes.. it is exciting but exhausting as well we moved out for 4 weeks while structural stuff was done and have been back in for four with about 2 weeks to go, very tough living, my best friend has been a $29 target electric frypan, I am the creative gourmet of electric fry pan foods , good luck with your job, ours is finally looking like it has been worth it. The only bad trade we have had is the electrician and he is going to be here in half an hour I need to get dressed and be ready to have stern words with him

If the budget permits, it may be worth spending some money on a landscape designer to come out and give you some suggestions and advice or even do the design for you. You can find designers local to you through professional bodies like Landscaping Victoria or AILDM. Most designers will actually have a consultation service. Even though it may cost a little now, it will save spending hundreds on something that doesn't work. Often AILDM or Landscaping Victoria will run Design Clinics at horticultural shows and events where you can sit down with a designer and get free advice. If you're wondering what to plant, talk to your local nursery as they will be able to advise what works best in your area. Just make sure you follow through with a purchase - no-one likes to be taken advantage of! You can also check out what the neighbours are growing as this will indicate plants that work with your soil and climate. A tip when designing for plants - if you want to get a layered effect in your gardens, make sure you have decent width garden beds. Where you can, go for beds at least 1.2 or more wide. I keep having clients that want that look but leave me with beds that are too narrow to achieve it! When it comes to installation, unless you're really good at handyman type stuff, get a professional in. It may be that you do things in stages to work with your budget, but again, this will save you money as it will be done properly and will last. In response to your specific question, if you have pets, I'd spend the extra money and look at getting instant turf. Getting a warm season self repairing grass like buffalo or kikuyu established from seed at this time of year is almost impossible. They have a long germination time (often up to 6 weeks), and need warm weather to germinate and grow. Even cool season grasses like fescue take time to germinate, and then time to get established enough to allow for regular foot traffic. To improve heavy clay, adding gypsum will help in the shorter term, but longer term, adding organic matter will be the best solution. Lots of compost, and mulch with organic material that will break down and add to the soil. This is better than adding a layer of topsoil, though in areas where you are going to put lawn, a lawn mix to a depth of 150mm is worth it. Make friends with your local arborist for cheap mulch. Don't be scared to plant smaller plants. While they don't provide instant impact, they will establish quicker, and often outstrip their more advanced counterparts in a short space of time. Good Luck!