Honestly, freshers week events are not the time most people make their closest friends. Yes, you can meet lots of people, but there are also often daytime activities where you can do this. Most people make their best friends on their course, as you do spend a lot of time together, and often have shared interests.
A good idea in order to meet people would be to join a society or two which interest you- preferably those based around some kind of activity, rather than just a subject area. If you're doing an activity you enjoy with other people around, you'll have lots of chances to make friends. Lots of societies are happy to accept people with no prior experience of a sport or whatever, especially if it's something not many people will have had the chance to try.
As you meet people, I'm sure you'll find people who are happy to walk home with you after dark.
Is the university aware of this condition? Sometimes lecture rooms can be quite badly lit (or some lecturers put the lights out to make the screen easier to see). Also, last year I had lectures which finished at 6, which in the winter meant going home in the dark sometimes. It would be a good idea to make the relevant people aware if they aren't already.