There are two relevant dates here to be shown on the programme issued for acceptance (see clause 31.2). One is the date of ‘planned Completion’, which can be changed by any event that affects the critical path. That is because it is linked (directly or indirectly) to all activities on the programme.
The other is the ‘Completion Date’, which can only be changed ‘in accordance with the contract’ and therefore cannot be linked to any other activity on the programme. That is because of the definition of the ‘Completion Date’ in clause 11.2(3) as being ‘completion date’ in the contract data. The contract does set out when the date can be changed, for example see clauses 44.2, 36.3 and 65.4, but it does not allow for it to be changed by acceptance of a programme.
In addition, the contractor is contractually obliged to achieve ‘Completion’ on or before the ‘Completion Date’, see clause 30.1. Clause 14.1 makes it clear that your acceptance of a programme cannot and will not change that responsibility, given the wide definition of the term ‘Provide the Works’ in clause 11.2(13).