Uprated fuel pump, turbo timer, blow-off valve and boost pressure adjuster. Possibly all these would be required for a turbo installation, but this is all that's on offer apart from some gauges.
Hi and I'm too far away from you to suggest anywhere for you to take your wheels, but there are quite a few members on here from Essex and SE London who should be able to point you in the right direction.
Good opportunity for someone wanting to put one on track. I wouldn't want to try and get all the required parts at this early point since their launch knowing what Nissan are like though