How can I stop an unexpected Windows 10 update?

Celia’s working day was almost ruined after she was caught out by an enforced update. Can she stop it happening again?Yesterday, I intended to take my laptop to visit a client, but when I was about to set off, yup, I couldn’t turn it off without allowing Microsoft to do its upgrades. We all know how long that takes, and I had a train to catch, so I ended up having to wing the whole presentation.
The infuriating thing is that I knew there was an upgrade around, so I had checked the po