Some kind person has damaged my boot (2014 black edition twin door) in a car park and driven off. As a result I need I new boot, but was wondering whether the metal section can be replaced without the need to replace the whole hatch?

Do not see why not as they are separate section joined by linkages but how difficult that might be to resolve is another matter.

You should've asked the car park company if they have CCTV and trace the offender, it's also worth going to the Police Station to see if they reported it, this can however get reported at a different constabulary so you need to ask, i.e the crash happens in Plymouth but the driver lives in Manchester and reports it in Manchester rather than Plymouth where the West Country cops will know nothing of it being reported, give it a week to be reported.