If she has no other income while awaiting One Parent Family Payment (which in truth may not come through for ages after the baby is born), she can apply for Supplementary Welfare Allowance at the local health centre. It will be means-tested, based on her parent's income until the baby is born (after that she's treated as a family unit in her own right). If she qualifies for SWA, this can continue until she is ready to go back to work, or until the OPFP comes through.
She should contact the Community Welfare Officer at the local health centre.