People’s voting patterns in mid-term locals aren't a very good indicator of who they vote for in a general election 2+ years later. Completely erroneously, people often see local elections as consequence-free and a bit like a popularity contest, when in reality local elections are pretty important at determining how your life pans out.
My main point though was that extreme parties trading on whipping up racial hatred are generally not very succesful in the UK. As a country, it’s too diverse, too educated, too much shaped by wave after wave of immigration.
People voting for Reform will also react very badly, by and large, to any sense they’ve been tricked, misled, or hoodwinked, and Reform have hoisted themselves by their own petard there - witness people who have had to resign because of their stupid social media posts or unpalatable history…