I need to get from Stratford to Deptford Bridge tomorrow, TfL website
seems to imply taking the DLR and changing at Canary wharf, does the
DLR not run direct from Stratford to Deptford Bridge?
I've not used the DLR before but the map seems to imply a nice simple
direct line.

Most Stratford trains terminate at Canary Wharf during the day. They
continue to Crossharbour during the peaks, and Lewisham in early
mornings or late evenings.