Hello lp60, welcome to Psych Central.

You will need to go back to your GP to be referred to a psychiatrist/mental health team. There should also be a free counseling service attached to your university, they recognise that it is stressful being a student which is why there is usually one within the university. Here is a link to Home | Mind, the mental health charity - help for mental health problems which has a wealth of information on support and treatments available.

Also, while you are seeing your GP, ask to see the diabetic nurse regarding your insulin, I'm sure that you should not be restricted to dashing home to do it. You are young and don't need that sort of restriction, it would help your depression to have more freedom.