Earlier quoted context omitted.
I live in the centre of Copenhagen, and haven't ordered anything from Amazon for a decade — on principle. I have ordered from online retailers in Denmark, and I've made 2 orders from AliExpress, and a few more from eBay. Can you give five items you can't buy in central London, but can buy from Amazon?
I have 400 orders on Amazon this year (I think that means I have more than 400 unique items since one order can be more than one items, but it's probably around 450 items total so not far off). Of those, I probably have a good portion which is household goods as I mentioned, like soap in bulk, soda cans in bulk, etc. which is cheaper than any other option (especially because I don't have a car in London). Then I have…
But anyway, shops selling luggage are common. They probably sell scales too. Argos, Tesco and Ryman have them.
Electronics shops like Currys have monitor arms, as well as office supply shops.
I won't guess what a good shower filter is.
Office supply and electronics shops also have label printers.
Moth repellent is available from large supermarkets, DIY stores and hardware shops.
All of these are also available online from British companies that pay their fair share of taxes.