On-page SEO for global and local

Hello, Thanks for the access to this group. :) I have a dumb SEO question. I`m working on the seo of a multiregional site and there is a global (in english) and there will be a UK specific site as well, as some products we offer only in UK but not all globally or in other markets. However, some pages are going to be the same on both sites, for instance general products page or `about us`. I`m wondering how to adjust on-page seo for global and GB as it`s sort of the same page (a few pages will be the same)? Should the content then be adjusted/edited so we don`t have duplicate content or should we have rather global page and create a /gb url that would redirect to the global one that fits also the GB market? In a case of a latter, do I adjust the on-page seo components to be on global page only or do both of the pages still need those details? Also, Careers page is in english and it won`t be translated to any regional language, how does it work when it comes to SEO? What are your thoughts? Many thanks and any help is much appreciated, Vedra