I got a call from my medical centre today telling me I was booked in for wednesday week for my second AZ dose "but we have an opening for tomorrow if you can make it in."

I paused, and waited for them to inform me that "however, if you have it tomorrow instead of next week your resulting immunity will be 25% less."

No such information was offered. It's a medical center, how about you giving me vital medical advice instead of relying on me being better informed than you are?