Why not just get a very light soft shell jacket/windshirt and add it to your kit? I'm assuming that you are wearing your Gore-Tex jacket when it is not raining as protection from the wind. If so, then the solft shell/wind shirt will do the job perfectly. Wear the Gore-Tex when it is raining, the rest of the time wear the soft shell. The combination will weigh much less and pack down much better than any cotton jacket you can get.
Fair point which someone made earlier. I have a pertex windshirt and will do just that. I guess the real question is how to best make the jackets robust enough for the woods. I am thinking of a cheap cotton smock to go over the goretex or spending more money for a lined cotton jacket (robust outer, waterproof inner).
Both options give less breathability than pure goretex but that is the price you pay for bramble bashing and sitting by fires!
I am from a military background and much is done **** about face. I was issued a cotton jacket and a goretex. The goretex was old fabric and heavy and many soldiers bought lightweight goretex or similar to go underneath the cotton jacket when things got really wet. We still carried shirts if the weather was too hot. I guess the next step is to take the outer jacket and line it with lightweight goretex. This is what many people seem to be making now for hunting and bushcraft and I was wondering how breathable they really are.
Taking separate goretex and oversmock gives more flexibility because the oversmock is the softshell also. However, when the weather is getting crappy, who wants to take of a jacket, put another on and then put the first jacket back on in the rain? Also, there is too much material on a full cut jacket to fill the place of the softshell. AND, a separate garment has another load of zips, pockets and fastenings that are surplus to requirement.
I went off thread there but thanks for pointing me in the right direction.