To be honest it sounds as though you are very late in the day deciding if all this globally is grounds for an NCE at this stage - it sounds like there should have been NUMEROUS compensation events to date.
There are a number of process that should/should have been followed along the way:
RFI - not an NEC term but a process that most projects would use and works perfectly well alongside the other defined processes within the contract. These should be used just where you need an answer to something and it is not too urgent - what colour do you want X, what position do you want Y etc.
EWN - where you are aware of something that could be an issue that could affect time/cost/quality then you should notify an early warning, which should prompt a meeting to discuss the matter and for the Project Manager to agree the action to be taken to move forward. This may or may not lead to an instruction, which in turn may or may not constitute a compensation event
Notification ambiguity or discrepancy - if there is an ambiguity between two contract documents in the Works Information e.g. drawing states X and the spec states Y, then you need to notify (in writing) to the PM of this fact. They then need to give an instruction to resolve that ambiguity, which will then be a compensation event. Under clause 63.8 the Contractor in this case will be assumed to have allowed for the cheaper easier solution where this is Client design. The difference between the two is what can be claimed in terms of cost AND time
Compensation Events - where ever there is a matter that constitutes a compensation event under clause 60.1 then you should notify EACH matter individually as a compensation event to see if the PM agrees it is one and then to request a quotation. Clause 20.1 states that you should provide the works in accordance with the Works Information. Any subsequent instructions changing the Works Information would therefore be a compensation event under 60.1(1). Certain compensation events you are time-barred if you have not notified within 8 weeks (see clause 61.3)
Programme - every period (normally 4 weekly or monthly) the Contractor should be submitting a revised programme showing where they are in terms of overall planned Completion. It should have been clear therefore period on period where you were heading in terms of how all this stuff was impacting your works. If ever you are showing planned Completion beyond Completion Date - that is either Contractor liability, or you need a compensation event in the system to equate to that delay. There is NO mechanism for an “EOT” claim or global disruption claim under NEC - any delay needs to be attributed to a specific individual event
Taking all this into account hopefully you can see what you should have done, and now what you need to do.