I would say it depends on which city you are in and how familiar you are with drunkeness on the streets late at night - whether here in the UK or elsewhere. As a female UK national I feel quite comfortable going out alone although I think most women prefer not to, purely because they find it more fun with friends.
If you wish to attend Fresher's events on your campus rather than in a town centre I would say you're probably safe whereas in town centres if you're not used to drunkeness on the streets and how to avoid worrying situations then you might want to wait until you've got someone to go out with. But, remember, everyone's a Fresher and everyone's going to the events, especially on campus, not knowing anyone so you won't be alone in that. That's the idea behind them!
Have fun! :-)