Maternity Allowance - how do they notify you?

Hi folks, I'm waiting to hear back about my Maternity Allowance Claim (not entitled to SMP as I'm self employed). All I've received is a text message saying it's being processed and that I will hear from them within 4 weeks. I have a payment from DWP pending that could be it however it isn't the amount I was expecting. Do folk receive letter or email with information on what to expect etc? Thanks!