The Nottingham Trent dip covers pretty much the same core material but it a different format. At one time before charter IOSH wouldn't accept Nottm Trent for full membership. I think that might have changed but check with iosh. I prefer the Nottm trent dip but I may be biased, I live in Notts.

I studied the Nottingham Trent OSH Diploma part time over two years prior to IOSH being chartered. It was accepted then for membership after so many years experience and for RSP (Registered Safety Practitioner) status. Notts Trent in those days largely consisted of lectures with a couple of assignments / essays per module with a dissertation. Probably helps if you like writing assignments. I never did a NEBOSH certificate or diploma. However one of our lecturers used to use past NEBOSH questions to 'challenge' us. The main difference I found was trying to guess what on earth the NEBOSH examiner was actually asking and I personally felt that the necessity to be able to interpret the coding within the question suggested an attitude from NEBOSH of 'we'd rather fail you than let you show us what you know'. As I say, it's my opinion. As a consequence I personally was always glad not to have grappled with the NEBOSH questions. I'd go Notts Trent or the NVQ route.