Hi Robbie,
I charge at £25 per hour + VAT per opperative inclusive of materials and equipment.
£100 per day is very cheap, the buliders will run you about if they think they will get away with it, charge them high and they will tow the line a bit more as I works out too costly otherwise. You will avoid doing a clean to be asked to reclean it due to a builder snagging works etc....
Hope this helps,
Trev