Canonical Tag URL

Hi all,
I’m having issues with Google Search Console. Think the issue is because my canonical URL is the following:

As you can see, it double’s up the URL for some reason?
Can anyone tell me what I need to do to change this from the back end of my site? Many thanks.

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

Having reviewed the source code the page does not have a canonical URL declared. I also noticed you have relative paths declared for internal links. I would recommend moving to absolute path URL declarations to resolve this issue.