It depends on many things, but also are within these guidelines. A splash back provides a surface which is to be impervious to water, therefore not allow water to absorb, and depending on your state, the regulations directly behind a water point including a tap or outlet is to be minimum 200mm high, and for heat and fire ratings, the area behind a cooktop needs to be 600mm minimum from your bench top is you have an electric cooktop, and 650mm for gas, with the splash back to extend 200mm either side of the heat source either side. So even if you want to only do this, there will need to be quite a bit of splash back, and often people use things like the bench top, window position and overhead cupboards to contain the splash back, providing you a rough idea of where to start and end one. Although not technically required, even in areas without services, a splash back that changes height and doesn't continue around walls to neatly finish off the surface will look out of place, so for consistency, the splash back is best used to effect, and provides an opportunity to incorporate a colour or interesting surface to the kitchen. By no means should a splash back be an after thought or put in simply in response to the minimum regulations. If you have a layout of your kitchen, start where your overhead cupboards are and draw a line around the entire room (even through windows and openings) to see it complete each wall that is part of the kitchen. Meaning any wall that has a bench top attached. Tis is a good place to start. Hope this helps.

I have used man-made stone such as Caesarstone on my client's bench tops for years with no negative feedback thus far. If you are looking at Caesarstone and don't want a stark white, then consider Organic White, Frosty Carina or if your budget runs to it, Calacatta Nuvo (a marble lookalike). If you like grey, before they released their concrete range I used Oyster. I agree with Focus Kitchens & Bathrooms, you would be better to visit a showroom and have a look at a large sheet of any you are considering. It gives you a much better idea of not only colour variation but the overall pattern. If you do use 'stone' on the bench top there is an emerging trend of running it up onto the splash back as well. This works well if your design style is classic or modern classic (transitional).

some more ideas, do you have attic space that could be used for extra bed/study this an economical way to get extra space and using Velux windows it work s well. Don't know what style of house you have but would you consider taking the front verandah for ensuite which could have slopping glass roof or better still opening Velux window to let air in and out, you could look at the stars. You mentioned the Lounge/living room to be kept to double as a study area, with the fireplace working that would be a lovely room, I'am suggesting large sliding door/s for when you want to close it off. An outdoor kitchen/BBQ for the blokes in the family would also work well cheers

Hi Nathan, I worry by introducing another colour, it might wreck the overall aesthetics to your kitchen. My initial thought was a white subway tile with dark grey grout so it’s drawing the grey/darker tones from your floor tiles & wall colour - while still lightening things up with the white tiles. You can always use colour with accessories to bring some spunk into your space :)