Missing national insurance credits

I’ve just found out I’m missing national insurance contributions for 2008-2009, I would have been in full time education and claiming child benefit for my child (from July 08) how do I go about correcting this?

Hi,
Before 2010, you only received national insurance credits for being in full time education for tax years you were ages 16 17 and 18.
If you turned 18 before April 6th 2008 you would not have received credits for the 2008/09 tax year.
If you turned 18 after April 6th you should have credits there, if so you need to write into us.
Please write to 
Individual Caseworker
PT Operations North East England
HM Revenue & Customs
BX9 1AN
include with your form or letter
•    the dates you were a student
•    confirmation you were under 19 during the gap (proof of Date of Birth)
•    any employment details
•    evidence of any earnings during the period for example pay slips, P45 or P60 
•    your personal details
•    your signature
Regarding Child Benefit or as the credits were called back then, Home responsibilities protection, child benefit must have been paid for a child under the age of 16 for a full tax year in order for us to award HRP credits. A tax year runs from 6 April to 5 April. If your child was born in July 2008, you would not have been entitled to HRP credits for the 08/09 tax year.
Thank you.