It's been running since 2000 Tom, but it's very low profile in England as we so rarely have a team in it, as qualification is by winning the Champions League & we don't do that very often.
Real Madrid & Barcelona have dominated it for some years now, winning it 7 times since 2009.
https://en.wikipedia.org/wiki/FIFA_Club_World_CupSo if you win the champions league, who do you play against? Do all previous winners qualify or sumert?
It's consists of previous season's Champions League Winners plus the Champion Club of the host country.
The "Champions League" we are familiar with is only the European version, but there are also Champions League tournaments every year in Africa, Asia, North America, South America & Oceania.
So, in total, 6 different Champions League Champs plus the Champions of the host country.
Previous winners do not qualify, no.