Generally speaking, you will always need to file a Self Assessment with HMRC each year, however, as you only started trading in October 2020 it'll be down to HMRC's discretion whether one for Jan 2022 will be required this time around.
I'd recommend contacting HMRC on 0300 200 3310 and simply ask them whether you need to file one for the financial period between 6th April 2020 - 5th April 2021 but do explain you only started trading in October 2020.
Be sure to have your National Insurance Number and make sure your personal details and address are up to date in your personal HMRC tax account or you could fail telephone security.
- If you do not already have a personal tax account, you can set one up here.
If they do require a Self Assessment, you've still got time to get one over to them before the deadline so no worries here 🙂
Hope this helps!