This link is for the ‘brown book’, which refers to the printed version of the Safety Representatives and Safety Committees Regulations 1977.
The 2015 version is the most recent PDF I can find from the TUC. The TUC has produced a 2025 hardcopy version which you can order online. The Health and Safety Executive’s website has a PDF version which is older than the TUC’s.
The regulations haven’t changed dramatically since 2014, but if you are going to quote them it’s best to check with the current versions of the Safety Representatives and Safety Committees Regulations 1977 (or the Health and Safety (Consultation with Employees) regulations 1996 for workers without union recognition).