Why dont you make a phone call without givinng your name to Inland Revenue and see what advice they could give Or make an appointment with a CAB advisor and ask about your tax credits.
Alternatively you could wait til you speak to the OR
Working and child tax credits are included in income, child benefit is not.You have to have more than £99 disposable income left after paying your living costs befre you get ipa though.I get both and up to now haven't got ipa(been told I won't get one,but I won't believe it till I'm actually discharged)