I remember this very well.
The quality was phenomenal considering it was a childrens' comic. We got Look and Learn and it was always the first item to turn to.
Other old folks might also remember "Jason January, Space Cadet", and one about a schoolboy detective
These started life in "Ranger" which was taken over and absorbed into Look and Learn.
I think it was a conscious effort to go upmarket away from the usual comics printed on bog paper [Lion, Tiger, Hurricane]
I think I probably got my General Studies A Level on the back of reading the history and science articles.
The Trigan Empire was a bizarre mix of Roman dress and high tech. A very distinctive look. The Emperor Trigo and Peric the scientist were in armour and togas and the next generation in flight suits.
It started out as "The Rise and Fall of the Trigan Empire", and initially the premise was that all the stories came from the chronicles carried aboard a Trigan spaceship that crashed on Earth. That premise was eventually forgotten or at least not referenced.
Why is my head still full of this sort of stuff?