Hi electrictalk. Just for everybody's reference, you've asked questions about this expansion of your site before, and I'm assuming the basic situation is described in this thread, which you posted about six weeks ago... Grow UK traffic for US news company July 31, 2019 https://www.webmasterworld.com/google/4957619.htm
It looks like you did not talk your CEO into getting a .uk
or a .co.uk
TLD, and that you are using a "uk" folder. If so, you will need to master one of the more challenging areas of tagging pages for Google... known as "hreflang".
Here's the main Google help article on "hreflang". I suggest you watch the video in the article more than once, maybe more than twice, and then read the page. Tell Google about localized versions of your page Use hreflang or sitemaps for language- or region-specific pages
As noted on the help article, one aspect of the scenario that you are anticipating is one of the situations that prompted Google to develop hreflang.......
Some example scenarios where indicating alternate pages is recommended:
If your content has small regional variations with similar content, in a single language. For example, you might have English-language content targeted to the US, GB, and Ireland.
There are many other aspects of content to be considered, but "hreflang" might be the most demanding, so I mention it first.
Also, you wrote...
I'm aware of duplicate content so if you have other advice than that would be great!
It's not clear what about duplicate content you're aware of, as initial discussions on WebmasterWorld actually took place over several years, and they continue constantly.
To some extent, "hreflang" is about one
aspect of disambiguating duplicate or similar content... but there are many more, and the devil is in the details.
PS: Sorry for being so foreboding about the process here. In good part, my additional advice, since you ask, is that you reconsider whether you and your organization are really up for doing this. I think that goodroi's second post in the other thread you posted suggests that this is really not easy to get right... and the questions that Maile Ohye is asking in her video are trying to suggest how much a multi-language site (which is what this is) is going to add to your company's work load, and how important it is to discuss that before you take it on.