for you Ggirl - so horrible to think of our children feeling like failures. It's probably no help but I only achieved 6 O levels back in the day, 3xB and 3xC. However, I have gone on to a First Class Hons and an Msc and a very respectable professional career. Some of us blossom at different times, different subjects and in different ways.
Ds is staying at his school for 6th form and is not changing his subjects (Maths Further Maths Physics and Geog). Geog have a field trip to Iceland but in general the school is very sensible about affordable trips although this year the Philosophy and Ethics group are trying to swing a new York trip! maths - they just get a few days out.
I think peer group is imortant, but probably less so the older they get and the more they know what it is they want to do. ds mixes with a wide group with varying aspirations but he has always had a very clear idea of his own wishes. He once turned round to a boy calling him some 'swotty' name or other in Year 7 and said 'why wouldn't I want to go to uni and get a great job?' which (amazingly) shut that one up! He has gone through school continuing to be himself and for that I am very very proud. Not one of his friends expressed surprise over his 9x9's and even the less able/aspirational kids have been lovely to him. I think the key is to find a school where the dc is happy and then they will flouish. We very much went against the grain and turned down a private offer and a superselective offer in Y7 for the local comprehensive where ds thought he would be happiest (and tbh we felt to was also a good 'fit' for him) and the risk paid off.