I'm thinking of building a porch out the front of my house. Probable
footprint of 2 metres square.

I'd like a oak frame, thinking of 8" square or similar oak pillars, with
masonry filling the gaps up to a height of 3' or so, then glass to the
ceiling.

Has anyone done such a project?

Where do you get oak pillars at a reasonable price?

And, planning permission, I believe there is no planning involved if it
is so small, and not above something like 2.2m. Any idea if that is
true?

Thanks
Alan.