Here’s your problem. You have:
Your main site: https://www.helenmortonphotography.co.uk/index.htm
Your blog: https://www.helenmortonphotography.co.uk/index.php
Since WordPress is designed to strip the “index.php” from the URL, as it should, all requests to the blog will wind up going to your main site, as it is the first index found alphabetically.
If you want your WordPress blog to replace your main site, just delete the index.htm file.
If you want to keep your main site, you’ll have to move your WordPress blog to another directory, like /blog/ . You can do this one of two ways:
1. Delete the WordPress files and database and re-install everything in a new directory. You will lose all of your blog content.
2. Move the WordPress files to a new directory. Follow this guide:
https://codex.www.ads-software.com/Moving_WordPress#Moving_WordPress_Within_Your_Site