I have just or I am about to change my URL for my business, will this affect my SEO? What steps can I take to reduce the impact?

This is a similar question to another Locafy Knowledge Base article concerning upgrading an old website, the answers are very similar

In this case, you should redirect pages from your old website to your new website. A redirect will tell Google about the change. It will help users get there too.

There are different types of redirects. The most common in this case is a 301 redirect which tells Google that the change is permanent. Additionally, you should add the URLs from the new website to your sitemap and tell Google about that sitemap as it may have changed locations.