Eljean, your husband MUST tell the HMRC that you will start working because the child tax benefit he is claiming is based on your household income. You MUST tell the HMRC every circumstances changed in your household so you can receive the right amount your husband is entitled because if you don't do this he will ended up overpaying of the benefit he wasn't entitled.
I'm sure they won't stop the benefit because child under 1 year old has a higher benefit entitlement compare to a child who is above 1 year old.
Contact the HMRC as soon as possible.