NEC4 now does this much better in section 65 of the contract. It is a whole new section on managing proposed quotations, including making it clear on what date the instruction will be given to proceed. It makes it clear on how this process is managed from when the PM initially requests the quotation.
However, if you are working under NEC3 then you still need to make the best of those clauses. Yes at some point along the way they should have instructed that they wished the Contractor to proceed with those works. That probably should have come at the point they stated that they were going to go ahead with their own quotation as it seemed at that point they could see that they wanted the Contractor to proceed at that point. If they have implemented the quote, it is pretty clear at that point that they wish to proceed, but they could/should have instructed that early to avoid any further programme issues.
However, if you are working under NEC3 then you still need to make the best of those clauses. Yes at some point along the way they should have instructed that they wished the Contractor to proceed with those works. That probably should have come at the point they stated that they were going to go ahead with their own quotation as it seemed at that point they could see that they wanted the Contractor to proceed at that point. If they have implemented the quote, it is pretty clear at that point that they wish to proceed, but they could/should have instructed that early to avoid any further programme issues.