I like the self-checkouts and find them quicker, but there are a few rules
1) Nothing age limited or in a security case that requires staff interaction anyway, just queue for the human when buying booze.
2) Unpackaged fruit or anything you have to weigh is a bit hit and miss.
3) Please please please understand the simple concept of showing the scanner the barcode, reverently placing the item in the dead centre of the scanner/scales platform thing and saying a prayer will not make it scan. I have seen far too may people fail to understand this, despite presumably having spent their entire lives watching the human operators do it. Ditto when its moaning at you to put the item in the bagging area, leaving it in your buggy/handbag/in another bag on the floor won't work.