I applied online. The process took 4 weeks. I interviewed at Waitrose (London, England) in Feb 2020
Interview
I had a group interview where we had to complete a task of sorting out events based on their priority. Then I had a 1-1 meeting with a manager to talk through my CV and followed by this I was asked generic interview questions.
The interview mostly consisted of role-play scenarios, which you had to explain to the interviewer on how to deal with. And then some questions about your skills, and your availability.
Very long, lots of group activities involving made up sales scenarios, which in my opinion was a bit over the top for shelf stacking and checkout work.
On the other hand, as a supermarket, they do have nice helpful staff - so there is probably logic behind it, it just wasn't what I was expecting.