Tax/NI Help - Employed As Well - Confused

Hi need some help here.
So early on in the year I setup my own business doing catering at weekends, used a government startup loan for capital. I also work full time at 40 hours per week. This business would have been weekend only.

Basically, I've had a tough year in that I've had stomach problems which lead to multiple hospital visits (usually at weekends, when most of my business would be done)... This lead to me having an operation which made me put off the business this year as it was to much to do.

I registered in April that I was self-employed (wanted to do everything properly). So now here I am, having used my capital, and made no earnings at all this year in my business.

Where do I go from here?
Carry out Self Assessment online?

Also I received a letter saying I had a payment due of £72 for National Insurance, class 2. But I've seen its possible to fill in a CF10 form for a small earnings exception? Can this be done online?

I paid full tax and national insurance in my full time job role.

Just wanted to do some more good and stuck now:(