Replacing hall floor - concrete insulated floor

[cascas]

I have a hall floor that has sunken in areas.

It appears that the original floor was filled with building rubble, topped with sand and the a quarry tile on top.

I am looking to remove the top layer and replace with concrete. Whilst at it I might as well consider putting in a insulated floor.

How should a new floor be put in, what dpc/insulation should be used. What thickness of concrete needs to be put in over the current substrate material.

 

[RedHerring2]

Working from bottom to top, you can easily work out how much to excavate:

at least 100mm hardcore (MOT type 1 is best)
50mm sand blinding (Builders sand is best)
dpm
100mm insulation (I think jabfloor is about cheapest) You might reduce this using other materials
dpm or lighter waterproof layer
100mm concrete
at least 30mm, preferably deeper screed