In BIDS for VS 2012/VS 2015 a right-click on the design surface didn’t show a localization screen. Hit F7 to edit the underlying code of the report where you can find the appropriate node and change it to your local setting:
....</ReportSections>
<Language>en-GB</Language>
...
</Report>
Replace <Language>en-US</Language> by <Language>en-GB</Language>
=FormatDateTime(Fields! UpdateDateTime.Value, dateformat.GeneralDate)
11/02/2018 17:01:25