Hi Andy,
Ok, so you need to install a plugin or a bit of code into your functions.php file in order to enable SVG file uploads.
Here are a few articles which will help you,
How to Safely Enable WordPress SVG Support (2 Simple Clicks)
https://www.wpbeginner.com/wp-tutorials/how-to-add-svg-in-wordpress/
Here is a potential plugin you can use,
