You have rights on employee information and consultation if you work for a company or organisation with more than 50 employees. Where the number varies, this is calculated as an average over the last 12 months. Some employers could choose to count part-time employees (those contracted to work 75 hours or less in a month) as half an employee for the purposes of this calculation.
The Regulations apply to public or private undertakings, 'carrying out an economic activity, whether or not operating for gain'. Because of the reference to 'economic activity' the Government believe that some public sector employees (mainly those who work for central government departments) may be excluded from the Regulations, but they have introduced a code of practice to extend the rights to these employees. If you are unclear whether you are covered by the Regulations, you should seek advice from your union if you have one.
Even if you work for an undertaking carrying out economic activity and have the required numbers of employees these rights are still not given automatically. Various processes need to be followed to obtain these rights. In particular, groups of employees will need to trigger negotiations with employees.