Is the Uno TTB LLU 40/10 Fibre Pro product running on the Business backhaul?
If you click on the Info sign next to the Pro products, the first paragraph reads: "Provided using the TTB LLU network, our Fibre Pro packages are available to all exchanges that are enabled for VDSL services and that are on the TTB LLU network."
I'm not sure why you are asking if the TalkTalk Business LLU product is running on the business backhaul. I would have thought the answer somewhat self evident.
Having said that, Uno use Daisy for the provision of their services, so it is a slightly different proposition from the TTB product that 23Prince was on. He is right that many ISPs use TTB for their backhaul services either directly or indirectly, including AAISP, IDNet, Uno, Pulse8.