They won't suffer for not going on these 'jollies' which IMHO are done largely for the benefit of the teachers (I used to organise them, so I know). Even many of the 'essential' educational ones are anything but...we have never bought into any of them and no one seems to have suffered educationally.
We went to Iceland (the latest 'must do' school trip) as a family recently and were amused and appalled in equal measure by the attitude of several large groups of English children who were in some cases standing around famous sites texting their mates, shuffling from side to side because their trendy clothes weren't keeping them warm and made them look totally ridiculous; and in others running wild inside hotels to the annoyance of others. I did actually ask some for the name of their school (expensive London girls' school

) and threatened to contact the Head if they didn't stop swearing outside my room. Happily Iceland is big enough for us to have lost them all by the second day.
Anyway, point is, don't worry about your DC missing trips. Use the money to do something memorable together is my tried and tested advice. £1600 goes a long way.

OT I know. Re schools- school is school.