I have been trying to save this page:
I tried Scrapbook on Firefox 56 and got that error. SiteSucker = same error.
DownThemAll! for Firefox did multiple URLs but still had the same NOCAPTCHA error for all pages.
I haven't tried HTTrack because I'm on OSX and haven't installed MacPorts yet.
Saving it conventionally via Save page as... I haven't tried yet, but that's because I was trying to find a way to save several URLs from the site.
Basically, I want to try and save all pages from within
http://www.geopostcodes.com/UK (and subpages)
I am on a Mac Mini 2011, using Mac OS Sierra.
I would appreciate it if anyone can help me find a workable solution to preserving pages for posterity for offline usage.