I'm doing civ eng at IC at the mo (1st year)
as lucykins said, there is an element of concrete, but no worries, you get hand-outs that repeat 90% of the content of the lecture in them (well, i fall asleep in those lectures anyway) and there's only 2 hours of lectures for concrete a week, so its really not significant... and its only for the 1st term. then you move onto metals, timber, glass... loads of other building materials.
they interview a fair number of people, but mostly dont interview the ones that are chinese (sorry, this is a little joke, but sort of true... its because they pay overseas fees).
in my year at IC, i remember about 3 of 4 people from interview day.
my interview was really chilled. i got an environmentalist interviewing me, so i wasn't asked any maths questions or anything, and to be honest, though the actually course is quite maths based, they do teach you all the things you need to know (i.e. basic mechanics, and maths is just further maths reiterated) I didn't do further maths, and i still got in, so no worries. its not like oxbridge.
chill, be yourself, and rave about why you actually want to do the course. (the 1st year coordinator is obsessed by the fact that people drop out due to a lack of interest rather than apptitude)
any other questions, just ask...