Yes, there is a Wendy’s in the UK.
Wendy’s is an American fast food chain restaurant founded by Dave Thomas on November 15, 1969, in Columbus, Ohio. As of March 2018, Wendy’s was the world’s third-largest hamburger fast-food chain with 6,650 locations, following Burger King and McDonald’s.
On April 24, 2008, the company announced a merger with Triarc Companies Inc., a publicly traded company and the parent company of Arby’s. Despite the new ownership, Wendy’s headquarters remained in Dublin, Ohio.
As of December 31, 2018, there were a total of 2, Wendys locations in the United Kingdom. One is located in London and the other is located in Manchester.
Conclusion:
Based on the information above, it appears that there is at least one Wendy’s location in the UK.