Hello since the Octavia is over 10 years old now are there any common places for corrosion? I'd like to get some protection in place to prevent any problems later in the cars life.

Virtually, everywhere- even on flat surfaces (!!) rust bubbles starts to appear. Looks like in factory they're painting dirty or rusty metal- and rust starts from "under-the-paint".
Based on my car and what I saw in forums and on streets: for liftback take a look at rear wing-bumper edge. 99% that rust is present. Even after 5 years.

Tolerances are too tight, parking backwards on curb pulls bumper <-> by stiff mudflaps (if installed) - and bumper tears paint off from wing's edge- and here we go...

But for Combi is not typical place- bumper is different.

I can imagine that after repair it's wise to glue transparent tape around this edge (and only then install bumper)- to "separate" bumper from wing.
Trunk lid horizontal edge (where license plate lights sits), rear wheel arches. For some Octies saw a lot of rust around door handles.
Underbody? Even after 7 salty Latvian winters all looks ok. Ok, exhaust clamp nuts/bolts are totally rusted.