I will be following your post - my plans are currently circle blobs on paper ;)

Here is a list I found... my son also suggested SketchUp.

Thank you both so much! I will keep you updated on what works best for us technophobics.

if you post a rough hand drawn sketch with dimensions of your original house (including location of windows, doors and all sinks and toilets) a site plan showing length and width of your block, distance from existing outside walls to all boundaries, location of north, a Google Earth image and/or photos showing the roof and a wish list i can make a basic plan for you and other HOUZZERS can offer suggestion but you''ll eventually need to have a draughtsperson make on site measurements and a final plan for Council and your builder but a floor plan app won't tell you how to fit everything in or know the building regulations and structural issues ....for that you will need professional advice but hopefully your builder neighbour has already advised about removing load bearing walls etc

Thanks oklouise! We'll try and get most of it together, then pass it to you for comment. I'd just like to mention that we will not be altering the footprint of the extension itself, except to remove two non load-bearing walls that currently comprise the passage. The intention is to open it up into one large space, with two separate zones - kitchen + relaxed diner-type dining area. The biggest change so far has been the removal of the old woodstove alcove and exterior chimney in the kitchen. It was in a bad state, leaking and leaning to starboard! Sadly it had to go. However, if we decide to keep the kitchen where it is, the wall it stood on will give us a blank canvas and some wriggle room to work with. The alternative plan is to move the kitchen across the hallway and into the old dining zone, the objective being that we will later re-fashion the current bathroom off the dining area into two zones - a walk-in pantry + a separate laundry. Since we are not going to make any dramatic changes to the existing extension, except install new windows and doors, Council and a draughtsperson are not really needed. Our aim is to gather as much inspo from the kind people here, as to what will be the best layout in both zones to suit our needs. This is the biggest issue we have faced so far! We can't seem to agree which side of the extension the kitchen should go, and the best footprint/layout in this area. Until we get that sorted in our heads, we cannot position the windows or doors!

I will take some pictures of the extension to give you a better idea, together with the dimensions and positions of windows and door. We plan to install a double French door off one of these areas, and have a full glass door which we'd like to use as a back door - so this would need to be incorporated into the plan. I had thought about positioning it where the old wood stove had been, but since that's on the west side of the house, it gets extremely hot in the afternoons. Give me a couple of days to gather it all together for you. We'd be so thankful for any input from yourself, and others. Design and layout are toughies! For the most part we are aiming for a "de-constructed" type modern farmhouse kitchen where less is more.

Hand drawn plans are still acceptable to most councils. Go with that or perhaps use Sketchup. If using Sketchup you could draw it in 3D or you can 2D draw too.

The advantage of a designer on board is that they know good design (obviously) and what is required for council approvals, in your case probably need approvals for new and/or relocated windows and doors, relocating kitchen (relocating a non habitual area to a habitable area and vice versa), etc., etc.

Hello Aussie Bush Girl, I would be more than happy to assist you: this is what I am best at! Getting plan right for you and your family. I do not do working drawings but the scaled sketch designs with all the plan, layout, construction, practicality, functionality and sensitivity resolved! If you would like to ring me we can chat about the best way forward and I will, no doubt ask you about 25 questions! We can do this via emails, phones and pictures. Look forward to chatting and fixing this for you. Cheers Margot