For NPPL it's a paperwork job as NPPLCo have to add the rating to your licence.
I've been teaching on a CTSW just lately and you'll enjoy it. Roomier, better view, better performance and at-least as good handling as anything you're likely to have flown before. Vastly superior to pretty much any common club light aeroplane in any respect except payload (which is not its strong point).
G