When a RAF VC10 goes into the hangar at St Athan for it's 5-yearly deep servicing, the tailplane is removed at quite an early stage and is then given lengthy refurbishment. I'm sure that any contributors to this forum who work at DARA will be able to correct me, but I think that a newly-refurbished tailplane removed from the previous aircraft is then fitted to the current "patient". I also heard a story that the RAF originally purchased a spare tailplane to allow this process to happen. Notwithstanding that particular rumour, the number of airframes that the RAF has aquired/scrapped would have easily enabled such component swapping to take place from the early-80's onwards.
The fin (definitely not "the vertical stablizer"
) remains firmly attached during the major service and I believe that the only time a fin-change has been required was after the BAe test crew nearly crashed the first K2 tanker during the flight trials - although, again, I am open to correction.