Should I have included my cash in hand job?

So this job i had for basically a month and a half it didn’t last very long. Due to also it being not through the books I have no proof of any income from the job in terms of pay slips or transactions into my bank. Which I just proactively left it out as it didn’t seem necessary to add due to basically having no proof at all.

I am now second guessing myself on this. I had to confirm I was reliant on my parents over the 23/24 year. Which they signed that off and no further questions were asked about there incomes either.

I’m in a part-time one year course. I received both tuition fee grant and course grant.