While you’re at it, what about the little bolts that adjust the wheel position in the dropouts of my P2? I haven’t measured them yet (still in situ) but you seem to have the cervelo specs memorised.
Dunno, I've never owned one. They're going to be a standard metric thread, so that narrows it down to M3, M4 or M5, you can tell the difference just by looking
M3×8 countersunk socket, available from any good online or bricks and mortar fastener shop, e.g. https://www.accu.co.uk/en/countersunk-socket-head-screws/5596-SSK-M3-8-A4
There will be eBay and amazon sellers too.