Argos Extra (Retail store) works like this; you walk in, place your order on an electronic machine (or go to customer services with a paper list of product codes), pay (which can be at the machine if you ordered by machine), wait 5-10 minutes, and all of your goods arrive via conveyor belt.

Here's the entire (customer-accessible) part of one such store:

https://c8.alamy.com/comp/2H6TX48/interior-of-an-argos-store...