Well sort of got an update, discussed all my questions/issues with the electrician today. Apparently my builders electrician does not touch patch panels, networking racks, etc. They said they will simply leave the network cables unterminated at whichever point I want and I will need to handle the rest of it myself how I deem fit. They would also not negotiate on pricing for network cables it seems or let me provide my own cabling for any purpose.
Depending on the quotes we get back, I will be asking them for comms conduits to be run (40mm) from the roof cavity to each room, and a larger conduit to be run from roof to termination point, and I will be having my friend come out to do the cabling for me.