I currently have a 1.6 zafira B for sale with excellent history for £1400, so make sure they aren't overpaying! I've owned mine for the past 3yrs/30ish k. My experience is they're cheap to run and insure, not uncomfortable but yes, pretty slow. They have a few common issues that are relatively easily fixed, but can be costly if you pay a garage.
Definitely a B btw, the early C's got the 1.8 Z18XER but not the 1.6. as tunnie says, 1.6T was much later and a different beast entirely.
As for rear space, with all 7 up, the only way for a buggy is to stand it vertical and put a Bungie round the rear most headrests to hold it up. Even then it won't do a double buggy, no way.
We did all our traveling in 2/3/1 formation which left plenty of space.