Maternity pay and holiday accrual confusion?

Hi, I am due to give birth on 5th Feb next year and have no intention of returning to my current job afterwards. I am aware that I will get smp for the first nine months (the company I work for do not offer any other maternity pay), but I've been told that while I'm off I should accrue holiday pay - is this right? If that is right, do I not get paid for it unless I go back to work and then take it as holiday - do i get paid for it anyway?