Tax information?

Hi! I’m new here and I have a few questions about tax. I provided my tax information but I’m not a US citizen. I’m currently living in the UK and I’m from the EU. I’m not very familiar with the UK tax requirements as I’m still a student. I was wondering if I need to declare any income I receive from sales to the UK government?
I checked this webpage and it’s stated that there’s a personal allowance of 11k that is not taxable? Thank you to anyone who finds some spare time to answer!
P.S. I have a National Insurance Number.