I forgot to mention, many thanks to all those who have posted on IuCs already. But I still don't know how I should approach this.

I am worried beyond belief by a letter I have received today requesting me to attend an intervew with the fraud unit of the DWP. My situation is this, I'm pretty naive to the whole JSA claiming process in general but found myself unemployed 6 months ago and started claiming JSA. During my interviews I'd asked what would happen if I was to find part time work and was told that anything over 16 hours would have to be reported and I would lose entitlement to JSA. Anything under 16 hours and I could continue to receive JSA as normal. Now 2 weeks into my JSA period I started part time work at about 9 hours a week. Since it was below the 16 hour threshold I continued claiming and signing on as normal. From reading these forums I've found out that I should have informed the DWP about this immediately. I've been so naive in this whole matter and can't believe how serious this could be for me. A criminal record really would mean the end of my life, my whole education and any professional career prospects down the bin. What lies in store for me? What should I be doing about this? My interview is only several days away. Thanks to any advice anyone can offer.