read your ES40, your signing booklet which has all the rules in it, and tells you that you have to declare ANY work you do, paid or unpaid. read the ES24, which you sign every time you sign on, where the declaration says, "I have done no work, paid or unpaid".
I wonder if they've called you in for an Interview Under Caution as you have indeed committed offences, and you may be in more trouble than you seem to think.
no one will be interested in what "impression" you were under. there are rules for claiming benefit, and they've been in your pocket all the time.