On the day, arrangements probably vary a bit between centres. But I think the general procedures will be pretty similar
For me:
Arrive to area where you could be asked to queue outdoors - gazebo with suitably distanced chairs and space heater if you needed to wait.
Floor markers everywhere to assist with spacing
No-one waiting when I arrived, volunteer greeter asked for my name, popped in to check I was on the list, came out and gave me a numbered ticket and checked temperature with a ‘point and shoot’ thermometer
Double checked by receptionist and given form and info leaflet, and ushered to (socially distanced) waiting room. Volunteer (?) double checked my form and told me to wait for ticket number to be called and urged me to read the info leaflet
Number called - went to inner corridor where met by GP who went through the consent procedures (checking the questions WhitechapelLass mentioned, ticking them off and countersigning form) and answering any questions. Waited there (on chair - no need to stand at any point) until person ahead of me came out - then in to actual shot from an HCA, who took form, checked it was countersigned, asked for DoB (checking it’s the right person), did the shot, did the paperwork and gave me my card.
Round here we don’t get next appt made on the day, we were told to wait for GP to re-open the slot-booking window. Also frequent homilies on not changing behaviour - still need to SD, wear masks etc
AZ jab, so no need to be surveilled afterwards
Hope that helps!