Yes, IIRC DHL already own the land immediately to the west of their existing building. The new building (which they already have planning permission for as part of the original permission IIRC) would go on top of what is currently one of the JetParks carparks.
And the airport has already laid new car parking at the eastern end of the airport. It's used for the 'Meet & Greet' customers cars freeing up those spaces from the other 'main' car parks.