Replacing a wooden floor and filling a 4' void.

Further to my previous question. The property is a 1910 terrace, 2-up, 2-down. The wooden floor joists have wet rot where they sit in the wall pockets - I have been advised to replace the floor. The front room is approx 4m x 3.5m. It has a traditional wooden floor. The void beneath is aprox 4 feet deep, and was designed to cope with water ingress - it isn't clear where from, but water appears to be seeping through the stone walls. The water level seems to sit at 1 foot, but can rise to an overflow drain just below the floor joists. Other properties in the street have water beneath, and some don't. So there are 2 problems really - drying out or filling in the void, and replacing the floor. Timberwise and Peter Cox Ltd are quoting to dry out the void (tanking, sump pump, etc). However, upon inspection both have suggested filling the void and laying an insulated and water proof concrete floor as the better solution. I'm looking for advice on whether to fit a sump pump and new wooden floor, or fill the void and lay a solid floor. Financing it will be a factor!