Over the past few months I have noticed water (2" deep)in the ground floor
void (approx 2'- 2 1/2'deep). I have checked all the main drains as it only
occurs during heavy rainfall. The water table is relatively high for this
area. I have considered filling the ground floor voids to either just below
the existing wooden floor joists or to complete the concrete screed at the
existing floor level. The fill would consist of hard core, sand blinding,
dpm, insulation, and concrete, floor joists and boards above. Concrete
screed to top that if I decide on finishing at floor level(within joists and
boards).

Anyone got any suggestions/advice?