This all reads rather oddly. You have been contacted by the Project CDM-C but you are not appointed to the Project. Presumably this communication has gone to all the prospective PCs on a Project Contract shortlist? At this stage, the CDM-C can only really write to you on behalf of the Client. By the same token, it is the Client who makes the appointment and it is he who needs to keep the CDM-C suitably informed. Presumably you already have a copy of the PCI for the Project and are being asked to submit some sort of method statement proposals as part of the Contract award process. A one-week window between initial CPP submission and commencement of the Construction Phase is entirely arbitrary and leaves no real time for challenge or amendment. I trust you have been advised of the actual time available for you to prepare and mobilise prior to starting construction - and hopefully that is more than one week!!!