Me again. When you say you'd have to pump 8 metres before an elevation of 4 metres, do you mean from a depth of 8 metres? If you do then that's the deepest cisterna i've heard of. If you meant pumping 8 metres horizontally before the elevation, then it's no problem.
Also, you could think outside the box and maybe consider having an extra water store of, say 1000 to 2000 litres at ground level to service the house, you could then top that storage facility up as and when required. An ideal small water store could be one or two ibc's (cubes) connected together and then, via your pump, onward to the house.
It all sounds so challengjng but many people here on the forum have already dealt with issues like this, so there's lots of advice available. Keep at it matey, you'll get there.