Some classic OU questions there, I'm not sure there is anybody here doing the Life Sciences degree but I'd say the answers for much of it are the same.
Basically, OU degrees are looked on favourably by employees, in particular due to the whole self-sufficiency aspect of studying on your own. Demonstrates how organised and motivated you are to be able to complete something as big as a degree independently. You can then go on to do a postgraduate at a "brick" uni if you so desire, loads of people have done that (I'm thinking about it myself).
120 points is equivalent to the course load of a year at other unis. I'm in my second year of doing 120 points and at the moment I am fairly busy, but I work 20 hours a week as well quite comfortably. As long as you are organised then you shouldn't have a problem with it.