Has anyone else found that when you click to skip a line of dialogue, it fast forwards the whole conversation so you miss everything else and the characters then talk over eachother.

I did a lil googling and found that Steam had made a patch to fix it. Any chance GOG will do the same?

Have you installed the 2.01 patch? Game's version 2.01 should be identical on both GOG and Steam.

By the way the so called "Benny Hill skipping" should have been fixed by an earlier patch, as you can read here.