When it comes to notification of a Project under CDM Regs, i know from HSE website that it says to notify HSE when you 'think' you are undertaken a project. So does this mean a CDMC can fill in the F10 even though they may not have a designer selected, and go back and finish the F10 at a later date once all information on the Project for the F10 has been gathered.

From what you are saying Emmet I take it that this is really early in the planning stage of the project and assume that the client was aware of his duties and appointed a CDM-C when the project is only a general concept. if initial detailed design work has been undertaken then a designer would be known and should have advised the client of their duty under CDM and would have been incuded on the F10 by the CDM-C. The ACOP says the CDM-C should notify soon after their appointment and that if there is information not available it should be updated as soon as possible after it is known using the F10, if you keep a note of the serial number when first filling out the online form you can use this to get back in to update when necessary. An initial best guess for start date and duration could be included on the F10 but should be updated if the actual dates for start & completion vary by more than about a month. Have a look at paras 19 - 24 of the L144 ACOP. On the plus side to all of this is that the client and CDM-C now have time to do competency checks on the prospective designers and principal contractors etc which I find is often not given adequate consideration.