https://www.gov.uk/government/publications/universal-credit-national-expansion

Tranche three starts from September 2015. Tranche four starts from December 2015.

(there appears to be at least one LA that is not on any of the four tranches..??)

Between April 2013 and 12 February 2015, 54,380 people had made a claim for universal credit across 96 jobcentres. Of those who had made a claim up to 8 January 2015, 35,260 had ‘started’ on universal credit (i.e. completed the claim process, attended an initial interview, and accepted a claimant commitment).