Manually calculating all those fees for each listing is tedious and you'll probably miss something. Different product categories have different fee structures, currency fluctuations change your margins daily. You can use an eBay fee calculator for UK here
https://easync.io/ebay-fees-calculator/uk/ . It breaks down exactly what eBay charges, what you'll pay in fees, and what your actual profit margin is before you list anything. Saves you from finding out you're losing money after the sale goes through.