If I have this right, 2.739 meters converts to about 9.000 square feet.
Depening on the size and qaulity of the clean on average you can clean 2000 square feet per hour.
Obviously we have not seen the lay out, density, stuff you have to clean, but I would at a guess say there is about 10 - 16 hours worth of cleaning, depending on the rota and how you actually clean.
You would require more than one meber of staff to clean an area of that size.
As for prices, its a fairly large contract and you would need to go in possibly at the low end to win.
Probably under £12.00 to be competitive to say the least.
I it will at least give you an idea of pricing per hour.
Best of luck with it.