I’m not an expert on Sainsburys, really. We just used to shop there. Most of it is self-checkout but they do have 3 or 4 tills with checkout workers down at one end. I guess you could walk through there. Also there’s a security guard who I guess could let you out.

I only put up with it once - about 3 weeks ago - and haven’t been there since. We’ve done our family shopping there for 15+ years.