+1 for Martins chipboard flooring.
I used the 8 ft x 2 ft waterproof, sealed surface, underflooring sheets (green then) on top of my concrete floor. The ordinary stuff had a softer, fluffy (ish) surface. Nearly 20 years in its proved very durable. Strong enough to take industrial sized machines and stands up to limited welding splatter just fine. The offcuts made nice shelves.
My floor is 8" of re-enforced concrete over 6" polystyrene sheet on a type 1 fill base. Never seems to get really cold.
Clive