I’ve done this many times before, and yet I’m not managing to do this again for some unknown reason. Tried endless solutions. Everything I’ve tried results in an endless redirect loop.

What is the best option for doing this?

Update 1
Here are a few of the things tried;

RewriteCond %{HTTP_HOST} ^website.co.uk [NC]
RewriteCond %{SERVER_PORT} 80 
RewriteRule ^(.*)$ https://www.website.co.uk/$1 [R,L]

And;

RewriteCond %{SERVER_PORT} 80 
RewriteRule ^(.*)$ https://www.website.co.uk$1 [R,L]

Tested in different browsers to prevent caching issues. Still nothing, just getting continual redirect loop.