Claiming Benefit where only one partner is eligible

Hi
I have Just received my ILR,and working 16 hour contract/PW. as previous Tire4 visa I have only claimed 25% council tax. we havn't claim any benefit before for the restriction apply. I will apply for my son MN1 to register for citizen as he born and live UK. My wife will apply FLR(m) and then later Set(M) for the settlement. She is Pregnant and will go for her maternity(Full time Working) leave next month for another baby.

I would like to apply for Housing Benefit , Child benefit for my son( 6Yr) on my name and Tax credit (Joint). is it will any effect on her future application as she is not/will not subject to Public fund until her ILR.

And shall I claim child benefit now or need to wait for my son to be register and get the British passport.

please share any ideas would help

Regards.