Been to and stayed at the majority of the Halls mentioned in this thread for at least a night, and live in private accommodation very near by julian markham and go to uni at lcc. Honestly, there's nothing to worry about at all.
By the end of the year you'll probably find yourselves completely enamoured with parts of South East London, especially if you go to camberwell...these places aren't beautiful middle class suburbs but I've really never heard of anyone actually getting mugged, robbed or stabbed or certain halls being targeted by thieves.