Your contract of employment should contain a clear written term specifying your rate of pay and other pay elements, which are a matter of agreement between you and your employer.
The written statement of employment particulars, which all workers must be given on or before their first day of work, must tell you your rate of pay, and when you will be paid (i.e. weekly, monthly, etc.).
You have some important rights relating to your pay, including the right not to be paid less because of your sex (the right to equal pay), or because of your race or ethnicity, or because you work part-time, or as a temporary (fixed-term) employee. Agency workers who have worked for 12 weeks in the role with the same hirer (including any agency worker paid through an umbrella company) also have important pay equality rights.