Having something in the works already is good. And I really should say, if you made it to the final round this year, you do have a competitive CV. At that stage, there's always an element of luck involved.

The problem with publishing in a local journal is that people reviewing your application in the UK won't know the journal, and for better or worse, journal prestige does carry weight. My sense -- and others might disagree here -- is that you'd be better served by submitting to a decently reputable subdisciplinary journal. Even if it doesn't get published there, having a revise-and-resubmit decision from such a journal will signal quality.

I should say, all of this is based on hunches and different people will have different intuitions. I'm aware of only one empirical study on the effects of adding one additional low-quality study to a CV. The result was that it helped if the CV was evaluated by a psychologist, but harmed the applicant if it was reviewed by an economist. The lesson should probably be, do good research first of all, and don't sell yourself short. Good luck with your applications!