Sounds fascinating but I can't see any photos yet. Maybe try to post again.

re the floor, what about garage matting tiles, as in photo attached, but lay them in a groovier pattern, perhaps a chevron or 60's pattern, if leaning towards MCM. It may not be any dearer than the cost after getting a tiler in, if laying tiles? Also, you can take them out to clean them if need to and change the look whenever you feel the need!

If you are still looking at benchtop options you want to consider our QuantumSix+ 12mm porcelain sheets. Measuring 3200x1600mm so it is ideal for a seamless long bench or the 6mm porcelain for a splashback. The 12mm is available in 2 colours - white with grey vein or white with a gold/grey vein (marble look). 6mm is available in 8 colours from marble look to industrial grey. Check out our website for imagery: http://wk.com.au/Gallery/QuantumSix-Gallery/8

anything is possible with enough money but with such a modest budget you might achieve the new bathroom and kitchen OR the extension but it would be difficult to achieve both at the same time but you haven't answered the questions??? what is the distance from the house to the back fence, what are all the floors, walls and roof built out of (ie inside and outside walls, concrete slab on ground, or is it a timber floor with crawl space underneath the house?? and NB where is north? ...what is the shape of the roof (hip or gable tiled roof or??) ...do you have an aerial photo of the roof like Google earth??...extending over the retaining wall shouldn't be a problem with proper cosntruction and there isn't anywhere else to go without losing the best outdoor area that has easy access to inside...the extra lengths of pipe isn't the biggest cost of new plumbing and a ventilating skylight will make a great light source for an internal bathroom...