So i've been doing some playing and re-installed using the packages but on CentOS8.
Once this was up i just created a simple zabbix.conf in the httpd/conf.d folder that pointed :80 traffic to /zabbix url.
Then did the same with a ssl.conf pointing it to /zabbix. Once tested and OK, then added a re-direct lines to the zabbix.conf file to go direct to https://
Guess a similar thing should work on Ubuntu.