The Equality Act 2010 protects people from discrimination in the workplace and in wider society. Protection against discrimination based on disability arising from mental ill-health is included in this Act. The UK government publishes a guidance.
Acas (The Advisory, Conciliation and Arbitration Service) provides free and impartial information and advice to employers and employees on all aspects of workplace relations and employment law. It provides a framework for positive mental health at work.
The European Agency for Safety and Health at Work produced a good practice report for mental health promotion in the workplace.