Working after baby

Hi all, not sure if anyone will be able to help me but here goes... First baby is due in January and when I go back to work I'm not sure if I should go back full time. Right now I don't qualify for any of the pregnancy freebies my midwife goes on about or tax credits. Not sure about child tax credits and how to qualify for that other than a combined income of less than ??60k? When I go back to work it's looking likely the baby will be in child care because I can't afford to give up my job. What I was thinking though is if I went down to 4 days that will possibly make me qualify for working tax credits so although I'm losing a day a weeks pay I wouldn't be paying for childcare for that day and I'd possibly be entitled to tax credits. Has anyone else done this or thought something similar and it hasn't worked out? I don't mind taking a small cut if need be but not the full whack ????