if you don't claim child benefit you wont get your cheque and as the benefit can only be backdated three months maximum I would try to get it done as a priority as you have missed out on over a hundred pounds already
you shoudl have got a form from the hospital or your midwife when your wee one was born but you can do it online
http://www.hmrc.gov.uk/forms/ch2.pdf
you need to send an original birth certificate along with the application
send an extract as I got mine back ripped even though I send them a stamped addressed cardboard backed a4 sized envelope
