How to get the html plaintext of full inspect table of Chrome or Firefox. New to scraping

This is my first post, hope not missing any rule here.

I want to make a script to get some info from many webs of a domain. The info always starts with a fixed string and, appended to it, there is another string (that is what I really want). I can find all this searching for the fixed string in the inspect tab of Chrome/Firefox and copying it outside (It seems not to be loaded at first, but it eventually shows up, it is inside an iframe I think). It would be amazing to download that Chrome/Firefox inspect table when fully formed, but I doubt is possible :(

However my objective is to get this info from a couple of hundreds of webs and I don't know how to do it automatically because I am new to scraping (I've got a txt file with all the URLs and tried some shell curls or copying some phantomjs code), tough I can program in C, shell or python with ease.

Btw i need to work with cookies but I think that shouldn't be a problem if the used tool has any way to add them (as phantomjs did). Sorry for the language, not English native here!

Could you guys tell me how could I approach this problem? Thanks.