Here goes the macro code where you can convert the language of PPT presentation into UK English. I found this code from here.
Sub LangInFrames() scount = ActivePresentation.Slides.Count For j = 1 To scount fcount = ActivePresentation.Slides(j).Shapes.Count For k = 1 To fcount If ActivePresentation.Slides(j).Shapes(k).HasTextFrame Then ActivePresentation.Slides(j).Shapes(k).TextFrame.TextRange _ .LanguageID = msoLanguageIDEnglishUK End If Next k Next j End Sub