lucky you! your water tank is below ground. I have to look at my 20,000 litre tank outside my kitchen window. It sits on a concrete plinth so I can't even plant around it. I'm too terrified to grow creeping fig on it incase it affects the integrity of the tank. At the moment it has wisteria draping over it, looks lovely in spring but deciduous and it's now becoming too invasive so need to get rid of it.. I also have star jasmine approaching from an arch beside - can't wait for it to take over the tank.. I love all the decorative features suggested but I reckon something like star jasmine might work with some other landscaping features to the side: bench, rock, more plants. The beauty of star jasmine is that it doesn't root, will drape over and can be pulled aside. Every couple of years I put the blower over the top of my water tank it to make sure the leaves don't mulch to create soil on top.

I wish I had thought of this with our previous build. Although our kitchen drawers weren't quite so wide, some of the runners couldn't cope with the load of heavy dishes I placed within them. Over time, the closed drawers would pop back open a little ways and this annoyed me. The current kitchen has wider drawers w/Blum runners, so I'm hoping for a better outcome.

Very light grey on all walls would be nice or white. Lighter colours like white tend to make spaces bigger and in ur case this needs to be done. The artwork on the weight bearing wall (in kitchen) needs to go as this draws ur eye to the wall . The railings on the stairs need to be painted (either colour of the walls or white)as this will help blend into the background and make the space look bigger.

Ok. Very first thing is to address your damp problem. Mould is insidious and very bad for your health. Get that right before you spend money on anything else. There is also no point in having floor area you won’t use.