Here is an extract from the handbook
(from my webpage, but unchanged from last year): 

"The assessor should
provide written feedback on the work undertaken so far by making
suggestions, corrections, and comments. 
...a copy of feedback should be returned to the student (and a copy to
the supervisor)."


The subtext is that this feedback can be quite "light touch" 
if things look to be going ok. The main objective is 
to catch any sign that the student might be going up a blind alley
of some kind, and if so to help guide them out.