Hello. I'm assuming that a lot of the answers on here were submitted by landlords, not tenants or anyone with any legal knowledge. If your door opens out to the street and in to a hallway then yes, in theory, anyone can knock on it. But if you have a garden, especially if it's fenced, or your door opens directly in to your living quarters, the one person who most definitely cannot make surprise visits is, you guessed it, your landlord. It's called "interfering with your right to quiet enjoyment" of your HOME. They seem to see your home as just their asset and they can do what they like, when they like. The best thing you can do is to get a video doorbell and don't forget to save/back up any incidents that concern you. You don't have to splash out on a Ring or other expensive brand. I got one on ebay for £35 and it picks up my WiFi even where my phone and tablet have blackspots. Ican'trememberthebrand but it mentioned the upgraded WiFi in the photos and the
description. The word "ESCROM" is in my head but I think that's the operating system, not the brand. Ask for permission in writing if you want to affix it with screws. I just use the sticky pads because my landlord is one of those who says everything is "no problem" but then denies saying it further down the line. I hope these horrible answers haven't upset you too much and I wish you well in the future.