If you don't know what an inspection is for, and if you over the years have spent time working with the regulators, perhaps you've already been inspected without even knowing it. I suspect the British Regulators already know all they need to about NWBO.
I don't get what kind of process you could be imagining. It makes no sense to me that they could approve the application independent of the in-depth checking to verify what is claimed in the application. Do you think they could approve within the 150 target window and then later do in-depth checking? What are they supposed to do if they then find discrepancies between what was claimed in the application and what they find visiting in-person inspections? Like they're gonna then be able to say, 'Oh wait, we take that approval back?' I can't imagine that these inspections are not a prerequisite to approving and not some kind of afterthought. What would be the point? They are part of the approval process hence that is precisely why they are a big deal to NWBO requiring intense preparation like mock inspections.