Well, that was utterly painless. The whole process was:
Booked service via the Tesla app, appointment confirmed in Guildford for the next day, sent destination to car from app, drove to Guidford and parked up, confirmed on app that car has been dropped off, went inside to get coffee, 30 minutes later got notification on app that car is fixed and new TPMS sensor has been installed, car location shown on map, get in car and confirm repair, drove home.
Man, that is nothing like the normal repair experience of sucking air through teeth and "I dunno mate, parts innit, could be a couple of week before we can get you in".