Contractor can proceed without design acceptance but it would be at their own risk. If it was subsequently rejected for a valid reason under the contract then any cost incurred would be down to the Contractor along with any time implications.
If the Contractor proceeding with the works could affect anything else then the PM can always instruct the Contractor to stop the works which they would have to obey, which would NOT give rise to a compensation event either.
If the Contractor proceeding with the works could affect anything else then the PM can always instruct the Contractor to stop the works which they would have to obey, which would NOT give rise to a compensation event either.