You do not always need to be an employee with a contract of employment to get Statutory Maternity Pay (SMP). Agency workers also qualify for SMP, as long as they meet the minimum requirements as to earnings and length of continuous service. The genuinely self-employed do not qualify. For more information see our section on Agency Workers’ rights.
If you don't qualify for SMP, you may qualify for Maternity Allowance, which is paid by the Government rather than through your employer. Follow the instructions to claim Maternity Allowance, using an MA1 claim form. Maternity Allowance, like Statutory Maternity Pay, is paid for the first 39 weeks of the maternity leave period.
And check the Citizens Advice website to see what other benefits you might be entitled to.