I'd imagine there would be plenty of spare pairs in those multicore phone cables running down to the MDF room
I only have 12 or so spare pairs in my lab.
So if they come out in the MDF room, that saves the hardest part of the cable run, through those full-up floor holes.
It's way better than that.
There is already CAT5 cable trucks from the basement MDF to the floor patch panel.
AND I forgot that I already had a unterminated CAT5E running from my office to somewhere down the corridor, almost certainly the comms cupboard, but I've never actually followed it. A viewer emailed me saying that every office should have one given what looks like CAT 5 trunks, and sure enough, he's right.
I looked in the comms record book but could not find any record of the (unterminated) CAT5E cable going back from my office. Just my old VDSL line and old phone line.
So looks like I have at the very least already got CAT5 down to the basement MDF (about 35m). So could either just extend that from the basement MDF to the storage room, or put in or use an existing if available ethernet switch.
So likely just have to pay for the cable run from the basement MDF to the storage room and patching.