I provided advice before with a reference on changing the default run level on your system.
You can find numerous (current even) information on this desired solution online, however I would like to recommend something someone else mentioned before: using Ubuntu server.
I think the name there throws people off but it is basically Ubuntu without the GUI/desktop. In other words, you mostly get the Ubuntu base you’re looking for without the added-on or extra GUI stuff that won’t go away (entirely) with what I initially mentioned.
This of course assumes you are comfortable with configuring whatever you need via terminal or command line… this includes WiFi if you plane to use it, whatever Kodi does, etc.
Excellent! I was wondering if there was something more bare-bone than Lubuntu! Servers aren’t scary I’ll be happy to use command line, just a bit rusty having not used Linux for a couple of years.