I did it last year and found it really useful. It T189 in the prospectus.
I found the photoshop tutorials really good. Very basic to start with but as I've got more advanced, the grounding I got with the OU has been really beneficial.
I did the OU for the same reason and it was not too bad keeping up with the course work. I did have to do some on the train which was fun!
It covers things like focal length, sensor size, use of colour, composition, aperture, shutter, ISO, The weekly assignments don't have to be done but actually shooting to a brief is a really good way to learn. There is one multiple choice paper and you submit ten images at the end with a little description of what techniques you have used from the course.