Why the concern about erosion, if flat ground. If flat, once filled to street level, it shouldn't be going anywhere. May need to shore up the perimeter of property, or at least what the house is sitting on. 1st house built was on land with slight slope, so backfilled, but just what the house sat on, as the rest was walled in anyway. Shored uder the house part with concrete & stone. Might want to backfill and shore up the whole perimeter since rice land, depending if neighbor lots is all rice land also. 1.2 meters, that's going to get a bit pricey. Might want to consider buying a ready to build lot, if an option.