haha, there are cockroaches all over the uni... you see them all squashed on the footpaths.
Dont bother about biology, i didnt do it, and i've been fine. Its only really one subject in 1st year you need it for anyway, and like kim said, its designed to bring everyone up to the same level. If you havent done bio, you will just have to pay a bit more attention in the first few weeks when they cover all the basics. Dont waste your holidays doing more study, you will need all your brain power for the years ahead.
Just wait till you get a fresh dog to dissect that has maggots in the back of its mouth.... not at all pleasant! Or worse, a live animal with a maggot infested wound.... ewwww
Much of our time is spent looking at insects under microscopes (mites etc) because you need to be able to tell the major differences in order to prescribe treatments. They are actually quite fascinating.
Honestly, after you have spent a week at a dairy getting your head shat on, having urine and mastitic milk splashed in your face, getting kicked, bitten, sunburnt and are covered in flies, insects will be the least of your worries! Dont worry, its all in good fun!