At the time of writing the Public Contracts Regulations 2015 on the UK government website remains the definitive source of information on the procurement processes that apply to UK universities. http://www.legislation.gov.uk/uksi/2015/102/contents
The University of Northampton is very conscious of its social and civic impact as a major purchaser of goods and services. They have produced a guide for other universities on the ways in which they can include social impact clauses in their procurement processes for major purchases.
The guide 'How to do "good stuff" when buying things' includes case studies and suggested ways of measuring impact.