Yes that will be needed - if you don't have the right Gap Tool/Fault mate etc then you will need to get your independent land rover agent to do it. Comes with the territory, if you make changes to the suspension then you need to recalibrate.
Me, if I want higher height I just push the button to my LLAMs system and raise the car to the height I want - no permanent arrangement that requires calibration and wears the CVs. At the normal onroad setting I can go to +35mm or to about +50mm (both of which are higher than your spacers) at the touch of a button. Likewise I can go lower as well.
Yes if you want to run the spacers fault free then you probably need to get the car suspension calibrated professionally.
Oh if you wanted a permanent lift why did you decide to go spacers over say "johnson" rods - achieve your same lift but no recalibration required and a quick 5 minute revert to "normal" if required?