Cutting hole in plastic (coated?) door

[Ed_B]

Hi all

My first post here I believe - unless it was years back.

We have a mostly plastic or plastic-coated front door with no letter box. I'm wondering if I can just go ahead and cut a hole as if it were a wooden door, or whether I'll hit some glitch?

Likewise an internal door that seems to be even more plasticky - looking to put in a cat flap there.

Pics attached. First 3 are the external door, last one (with finger marks) is the internal one.

Many thanks!

External:

Internal:

 

[Ed_B]

PS the wood grain effect is just that - an effect. It's all plastic on the faces. I don't know what to expect inside - break my drill, wreck the door? etc.