My upgrade is due to be delivered tomorrow so I can tell you then.
Yes they text and email you to confirm the order.
I explained the process here https://community.o2.co.uk/t5/Discussions-and-Feedback/O2-upgrade-Experience/td-p/1460941
No texts at all when doing the sim swap for an upgrade.
Track usage, upgrade and get support with the My O2 appDownload My O2