Declaring tax on side hustle

Hello, first time poster here. I have a full time PAYE job. Additionally, I have a side hustle at Christmas assessing applications for the Chevening scholarship. This year, I earnt more than £1000 from this side hustle (approximately £1200). It's a one off payment I receive for this work. As this is over the £1000 threshold I believe I have to declare this additional income to HMRC. This is the first time I've done this so would appreciate any guidance. I'm finding the process quite daunting to navigate. So, I have my Government Gateway ID and I have registered for Self Assessment declaring myself as a Sole Trader - is this all correct so far? Once they've checked my application, I presume I then need to complete the Self Assessment Tax Return. Correct? I thought I'd post here in case anyone else has been in a similar position. Thanks, aperci123

Hi aperci123,
Yes that is correct you will receive a Unique Tax Reference, UTR, once your self employment registration is processed.
You will also receive a notice to file your tax return. Once you receive your UTR you can then enrol to file your Self Assessment online using your online account. Once enrolled you will receive an activation code and once entered you can then file your Self Assessment tax return online. 
Thank you.