I'm planning on infusing some sandwich panels that will be 1 outer skin of 200gsm carbon 5mm perforated PVC core and 1 inner skin of 200gsm carbon. Will it negatively influence my infusion if I only put peelply on the inner skin (bag side) where I plan on doing secondary bonding? The whole thing would have a layer of P3 film and flow medium on top of it.

unless you are going to mill out non standard grooves, just buy the core pre-drilled. It's not worth the time on the CNC.

To some extent my core choice reflects what is easy to get in Portugal. Also, as I have the CNC machine it's not a big deal to have it drill holes.