Payment of eBay shipping and confusion of income tax?

Hello! I have a simple and quick question that I was hoping that someone here could answer: I buy and sell products on eBay and I was wondering. I fix it myself, so all the money from the sale, including shipping, goes to my bank, and then a piece comes out for shipping (the next day, usually around £ 5-10 depending on size). As far as I know, I am paying the income tax on all the money from the sale, so I can claim the shipment as a business expense or something similar, or not declare it as income even …

EBay payment shipping and income tax confusion?