Hey Edd, I was in the exact same situation when I started University this year ( We start at the start of the year in Australia having summer during Dec- Feb and all), Regardless I ride my bike everyday of the week to Uni. What I would suggest is to find some very casual looking gear. I have boots, kevlar jeans, Leather jacket, gloves and a helmet. As soon as I park my bike I attach my helmet to the hook under the passenger seat and lock my bike.
People at a University will not mess with your bike in a car park, especially if it is parked with other bikes, they are intelligent people and will have better things to do, plus with people going past 24/7 they will be instantly caught.
I chuck my gloves into my backpack and then all that separates me from all the other students is my leather jacket which is stylish and I just throw over the back of my chair when i'm in class.
So the only gear I have on is boots with normal looking jeans over the top.
Also if it is too hot to wear a jacket you will be carrying it, which is never far as you will only ever be walking to somewhere where you will be sitting down again. Plus the jacket is a great conversation starter. I walked into my first lecture with my helmet and the cute girl sitting next to me saw and asked 'oh sweet do you ride a motorbike'? To which I replied, 'No, i'm just a really bad driver'. Gets a laugh every time and they are sure to remember you.
Eventually if you get sick of that the reception lady in the building of your faculty will often look after your gear while your there for the day.