Batch saliva tests are being worked on. The actual test itself I don't think there's that much quibble with, it's how large a group do you use and which group and is it as practical in the real world as it sounds. There could be large downsides if it's misused. Not in this country but elsewhere sewage analysis seems to be taken seriously.
The normal saliva tests are going on in southamptom and Manchester, but rumour yesterday was validation problems. There weren't enough people in southampton getting the virus to demonstrate it's 99.8% accurate and 99.8% specific and in a realistic range of people. And no data has been published.
The graph I saw said 800,000 tests by the end of November and increase into the millions in december and early 2021.