Hi Siu Yee Yum,
There is no clear answer to this question, that we can provide on this forum, as there is no statutory definitin of a 'trade'.
You will need to review the guidance at BIM20000
onwards, to decide if a trade or the venture in the nature of a trade exists.
For a more indepth review of your personal circumsances with regard to trading, you would need to call the self assessment helpline
and seek the advice of technical support inspector (TSI).
They would be able to review the Business Income Manual with you, to help you make an informed decision.
The self assessment helpline numbers are:
Number: 0300 200 3310,
Text Relay: 18001 0300 200 3310,
Overseas: +44 161 931 9070 (Open Monday to Friday 8am to 6pm. Closed on weekends and bank holidays).