Hi Christine,
OK, so the good news is that I don't think this is an international SEO problem. As such you don't need to worry about switching to a .co.uk or anything like that.
The keyword your going after isn't particularly competitive and the competitor that's ranking ahead of you right now looks totally beatable.
As Google are already favouring this page (i.e. this is the page that's ranking) - <cite>www.ldnwicklesscandles.com/scentsy-uk </cite>
I'd be inclined to build some more links to this page to push it up the rankings.
Given that you actually have products (always nice to have physical things when link building) - I'd suggest offering some products to bloggers to review / give away. A handful of decent links should see your rankings improve pretty quickly.
NB - you might want to re-work this page slightly depending on what you think the user intent is for this sort of keyword - e.g. are people searching for Scentsy UK looking to buy products or become a seller? My gut says most people probably just want to buy products - but I could be wrong!
I hope this helps,
Hannah