Claiming Tax Credits: Evidence of Class 2 NI

[Kennyoye]

I am applying for tax credits. Its a joint application. I am self employed as a director of my company. I have filed all necessary accounts for 2011/2012 including Corporation Tax and my personal self assessment. Moreover most times in a year I work in an employed position as a staff in retail with pay slips and NI payments. My wife is employed in the Care Sector and she has enough evidence to support our claim. However, for myself HMRC sent me letter asking for information about:
Details of trade or business qualifications
A breakdown of the hours worked per week
Evidence of class 2 NI registration
between Jan 12 and April 12, 2012.
Please what kind of documents do I need for the above and if any has a template I can use to support my claims, please do help. Thanks