Hi Sarah
Planning is essential!
filling breakfast ( I have flaxseed with hot water and it keeps me full from 6am to noon).
bottle of water (or travel mug of tea/coffee) to sip on bus
bus snack in case you need them (almonds or seeds in small plastic pot, mini cheese or sausages
(many buses have wifi so great opportunity to do study on bus which will leave you with more time with OH)
Lunch - take your own packed lunch!! Lots of students take their own lunch, most unit will have an area with tables etc, Universities are generally terrible as far as low carb options go. Typically sandwiches, wraps, pizza slices, pies, chips etc - salad bars are usually filled with pasta and rice options. If you are on a out of town campus you might not have many other options as lunch break time restrictions and location may mean you can't get to supermarket etc.
If you are in a city campus then there will be lots of cafes, coffee shops etc but again these are not always low carb and are expensive if you use them everyday (and they have too much temptation!).
If you are a post-grad then typically you will have access to a postgrad area with kitchen facilities such as microwave, so homemade soups, stews, leftovers etc are great way to control your own BG levels
Finally
inform your tutor (if you are undergrad) or academic advisor if you're a post grad) of your diabetes. Then you won't be penalised in terms of missing tutorials, assessments etc if you need to attend diabetes reviews, eye exams etc.
If you are injecting the university has to provide a suitable area for you to inject (if you want to use it or not is up to individual) and a sharps container