.htaccess将域映射到public_html中的子文件夹

I have an apache server for the system https://theveganhut.co.uk ; I need to have different sites in the same server. So, I put the files for http://theveganhut.co.uk in a folder theveganhut.co.uk in the public_html folder.

I have mapped the domain theveganhut.co.uk to the folder theveganhut.co.uk via the .htaccess file in the root(public_html)

<IfModule mod_headers.c>
  Header set Access-Control-Allow-Origin "*"
</IfModule>
RewriteEngine on
RewriteCond %{HTTP_HOST} ^(www.)?theveganhut.co.uk$
RewriteCond %{REQUEST_URI} !^/theveganhut.co.uk/
# Don't change the following two lines.
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /theveganhut.co.uk/$1
# Change example.com to be your main domain again.
# followed by / then the main file for your site, index.php, index.html, etc.
RewriteCond %{HTTP_HOST} ^(www.)?theveganhut.co.uk$
RewriteRule ^(/)?$ /theveganhut.co.uk/ [L]

But when I load the url http://theveganhut.co.uk/admin , the admin login page is seen, but the URL changes to http://theveganhut.co.uk/theveganhut.co.uk/admin/. I want the url to be http://theveganhut.co.uk/admin/

Is there something I am missing in the .htaccess file to address this issue? Please help.