The junior school dc went/go to start with 1 night away in y3 through to 4 nights away in France at the end of y6 with a few extras thrown in if you're particularly unlucky, and there's also a week's ski-ing trip in Y5&6 if you want it.
DS1 didn't want to go on any of them so he didn't, was very happy with that as I didn't particularly want him to go and I think it's much too early. He did go on a single night forest school camp through school but it was a much smaller group (it's a big school). When he first went to the school they used to reckon that maybe 10-20% of the dc didn't go on the trip but by the time it got to the Y6 french trip I reckon about half didn't go, probably not helped by there being a terrorist attack nearby, around the time we were supposed to be booking it. Ds2 is now in the school and also quite happy not to go, and it seems that about 30% of his year didn't go when he was in y3.
It does hack me off (and I have complained to the school about this, I'm not just venting on here!) that because they send so many people on the trip, they soak up all the extra staff to go with them for ratios. Which means that there are no extra staff left behind to take the dc left behind out even for a day to do something. This would be 40-60 of them so a significant number and more than enough that they ought to be doing some proper activities with them. On the one hand they sell the trips by saying that it is important that the dc get these experiences, the activities, the skills, the team building etc... But not so important that they can't sort out a similar set of activities locally for even a day rather than a week (apart from being in the midst of French speakers, they could do most of the things on most of the trips within 5 miles of the school without the need for an overnight stay). Instead they get to stay in school with a skeleton staff, doing bare basics and getting to watch films, or spend a day cutting up magazines to make a collage etc etc - nothing like the activities being done on the trip.
Sorry, bit of a rant there but it really annoys me that they treat the dc that stay behind like second class citizens. I understand if there is just 1 out of 30 it is more difficult to sort something out though!