The National Cyber Security Centre has launched a new reporting site that enables individuals to report suspicious websites they encounter.
Reports can be submitted online through the Report a Cyber Incident or Cyber Incident Signposting Service (CISS) at the National Cyber Crime Security Centre. The main page of the blog also has this link under NCSC advice.
Never click on any links in suspicious texts or emails, but if you come across a suspicious website, it can be reported to them as above.
https://www.gov.uk/guidance/where-to-report-a-cyber-incident.