Thank you so much everyone for taking the time to respond. Your first photo siriuskey is the colour scheme I'd love to go with so good to hear that you'd think it would match with the blonde brick. I also like the shale grey roof idea butterflyroof and you're right that you don't see much of the roof at all (mainly when looking out the upstairs bedrooms). The olive green is definitely another possibility to look at oklouise and I've made a note to use 'mid-century' in search terms. Definitely plan to pressure clean bricks and a bit relieved to hear that leaving them is the better option. I'm still finding it hard to imagine a darker grey cladding like monument with the blonde brick debluc but it's certainly been suggested a few times so I'll keep searching for inspiration. Thanks again :) (attached is a photo of a house near us that I like and that has a brownish tinge to the cladding that would hopefully work with our bricks as it seems to work with their sandstone - maybe dune colourbond?)

if the original asbestos walls are in good condition then they can re-be painted but if the walls are too damaged to be saved the asbestos needs to be removed by professionals and the cladding replaced, no reason you can't have different profiles on the front and sides as long as joints and corners are sealed properly but if you plan to install new windows it could be better to wait to repair sections of wall as the windows are replaced (i'd prefer to have all the roof and external walls in good condition and then do the internal work at leisure)... .modern fibrous cements are excellent ...we've just used flat fibrous cement with curved battens over joints and very happy with the results for our 50's house (there are several different brands available through the big hardware stores and research on line is much easier than trying to work out the variations in store) the gabled portico can be made as a separate structure or as a extension to the roof with valley gutters depending on placement of the solar panels (and/or solar panels can be moved)

I have to agree it was the landscaping and the imbalance of the colours that I noticed. From your additional comment I am not sure how important it is to you, but if you don't get it right a different colour won't work any better than the existing one IMO, and if you are going to replace the windows probably do that first, the different proportions of cladding and glass will change the look too. Btw how high is the railing? I know of people who had to change their railings due not being compliant with modern building codes. If you are having work done on the front you might as well find out about that at the same time and update if necessary.

One of my recent projects was a glass and brick contemporary extension that was built as a separate pavilion and linked with a small glazed link to an existing Victorian weatherboard home. The break between new structure and old structure worked well for different floor levels and roof structure. My clients were thrilled with the result. https://www.houzz.com.au/projects/1093664/modern-addition-to-victorian-home Here is a photo from the glazed link showing the lightwell space between the old weatherboard structure and the new brick structure. A consistant colour scheme ties the two halves together visually. If you are at the early stages of thinking about an extension it is too early to try and visualise it. Once you have provided a brief and defined a budget to your designer it is their job to resolve an appropriate design solution, present it to you, and communicate the design intent, with enough drawings so that you can visualise it. There is no point in trying to visualise expensive glazed white bricks for your extension, when your budget dictates painted, lightweight cladding! Best of luck, Dr Retro of Dr Retro House Calls