Selling gifts I received

Hi, I'm a big customer for an online shop. Myself as an individual, buying products with my personal money for personal use. No business affiliation at all. I'm not an influencer or any such thing either. Just a common customer who spends a lot of his money in that particular shop. As a consequence, this online shop often sends me a single unit of a newly released products as a gift. A different product every time. This shop hopes I will like those products and leave a positive review for them. But I'm under no obligation to leave a review, much less make it a positive one. I'm trying to highlight that there is no business contract or such between the shop and myself. I keep some of the products and use them myself. Some others I gift to friends or donate to charity shops. Some others I sell in online marketplaces. Regarding the ones I sell online. I saw some comments online about rules around people building businesses around buying and selling items for a profit, without registering nor reporting to HMRC. I couldn't find a specific example from HMRC about my scenario, though. I understand that in my case these are my personal belongings that I'm getting rid of, once a month or once every two months. Therefore, this activity of mine doesn't raise any tax implications I should concern myself with. Could you please clarify whether my understanding is correct? Thanks in advance

Hi,
Please refer to please refer to Selling online and paying taxes - information sheet
Thank you.