Which 2 are you doing?
I found Child Development really interesting but the books are pretty big. Cognitive is good too and the books are thinner although you have set books as well. Social Psychology I found hard going but still quite enjoyable.
I would say that you could do it in less than 30 hours but you might need to compromise on what you read and you may not be able to cover all the course. It isn't absolutely necessary to have read everything but you do need to cover enough to do the assignments and to make sure you can do a choice of questions in the exams. Perhaps get some past papers from OUSBA and keep an eye on the type of questions they ask as you go through the course.
The study guides are a sort of condensed version of the course so for the bits you don't cover properly, you can get a bit of info by reading the study guide.
My concern for you would be if your essay deadlines come at the same time, which is possible as that would be v. hard work. Definitely try and get ahead when the books arrive - if you are lucky they will arrive before Christmas although I am still waiting for books for my course that starts on 3rd November so there are no guarantees.
It all depends what else you have to do in your life and how much help you get with family life. I was mostly restricted to evenings and a few hours at the weekend so I would have trouble doing 2 60 point courses but if you have some day time free it would be easier.
Good luck though - I hope it works out for you.
It depend also on how good you are at making concise notes which I am rubbish at. My notes take up pages!