my head is in a spin

god ladies this is soo complicated, i'm really begining to worry about pippa going to childcare when i go back to work in january (i know it's a long way of) and i'm trying to work out if i could go back less hours. I work 12.5 hour shifts but get paid for 11.5 after breaks are taken of. I was going to go back 34.5 hours which is three days a week but would like to go back 2 days a week (23 hours) we won't get any extra help in the form of tax cradits even though my wages would drop by nearly ??7000 a year. I've gone onto the inland revenue website and got the information on tax levels and ni contributions and after a series of very complicated sums have come up with two figures. After working out tax and ni diductions and taken childcare of for working nearly 50 hours a month more i'd get ??100 a month more!! Now dh is going to look at his payslip when he gets it and check as if i worked 22 hours i'd be earning nearly the same as him but if i'm right i think i'll be going back to work for 22 hours it'll mean less spending money but the thought of working all those extra hours for only ??100 a month more does not appeal and pippa would only need childcare for 1 day a week as dh would look after her the other day. Either way when i pass my driving test i can't afford a car so just hav to see what happens,
Please ladies cross your fingers that i've done my sums right for once in my life
xx