You have to claim maternity allowance instead from the government, just go on their website x
Like Amelia said, it’s maternity allowance directly from the government. If you google it then it’ll tell you how to apply, it’s a long process though so start asap
They need to complete an smp1 form to explain why they won’t pay. You then need to complete mat allowance form and include your mat b form and payslips … https://www.gov.uk/government/publications/maternity-allowance-claim-form
I claimed mat allowance in my last pregnancy, start chasing your agency to do the smp1 form now as it seemed to take my one a while to do it and get the form completed as again it’s a bit long winded and you need to gather other bits of evidence. I’d also do the turn to us benefit checker as you might be able to claim universal credit on top
They have to give you an SMP1 form and you have to fill out a maternity allowance form x
I think you need to apply for universal credit. You won’t be entitled to anything before you go on mat leave but best to set it all up now x