Tricky!
One method is to track down which company hosts the website and to then contact them to request that the website (or the relevant content on it) is removed. To track down the hosting company, enter the URL of the website here:
https://whatismyipaddress.com/hostname-ip
That will provide you with the 'dotted quad' IP address of the site (such as 104.28.30.229). Click on that to find out the name of the hosting company and their location. You can then google for their contact details, possibly including the term 'abuse' in your web search.
You can also sometimes find an 'abuse' contact via a 'Whois' search. For URLs ending in '.uk', search here:
https://www.nominet.uk/whois/
For all other URLs, search here:
https://lookup.icann.org/lookup
With the UK leaving the EU (but, during the transition period, still being subject to EU laws and having already signed many EU laws into permanent UK legislation anyway), the situation regarding UK citizens 'right to be forgotten' from Google searches isn't at all clear to me. However, assuming that the right still exists, you can get Google to remove the relevant link (i.e. any including your name, going to the false information) from their search results by using this form:
https://www.google.com/webmasters/tools/legal-removal-request?complaint_type=rtbf
(Note, however, that the actual content won't disappear; it will simply cease being accessible via a Google search. Note also that, although the search result will disappear from Google.co.uk, it will continue to be accessible via Google.com and through alternative search engines).