Guys
You are getting well on your way to membership of the Institute of Civil Engineers
£6,666 per m3 of concrete ?
Current typical price of ready-mixed concrrete is £50 per m3, ex-works. I know there's more to it, but it gives you an idea. For a project of this size you would have a concrete production plant (known as a "batching plant") on site. Perhaps the one used on T5 could be sent over to reduce costs. Has anyone asked ?