@praelicious Forms gets it date format from the browser, so make sure that your browser laguage settings are set to English (United Kingdom):
Then when you view the form in the web version or in Preview as in the image below it will display the date in dd/MM/yyyy format:
But if you embed the form in a SharePoint page as in the image below it will still show the date in M/d/yyyy format and unfortunately there is no way to change that.
Microsoft obviously don't realise that not all their users live in the US. Basic date functionality that works this way, or doesn't in the case of the Forms web part, is lazy development on their part.
Intranet, SharePoint and Power Platform Manager (and classic 1967 Morris Traveller driver)