It is not true that the scout troupes are always mixed (regardless of the age of the children). As far as I know the youngest ones (beavers) are usually mixed but after that many / most places run two separate groups for boys and girls. The camps are however often mixed.
But the organisation depends on the scouting group active in your area. In Zurich there is even a Seepfadi ("lake scouts" would be the literal translation).
I used to be an active scout for ages (brownie, scout, leader, camp leader, international camps I did it all

) so PM me if you need specific information.
Word of advice: the system is different. Scouting is a youth organisation which means its run by young people, therefore the leader of the brownies can be as young as 14 to 15 but will then be paired with more experienced (but nevertheless young) leaders. its not better or worse than the UK system but different. But you will soon realise that this will not be only thing which will be "different"