I did my BEng with the OU after 10 years out of studying. Took me 10 years (changed jobs and wives etc). I am now 2 years into a 5 year Part Time MSc. Only advice I can offer (on a do as I say not as I do basis) is try to plan out the assignments so you don't have to take panic holidays from work to hit the deadline 
Also don't be disheartened if you only get 60% for what you thought was a good essay, apparently thats how they mark post grad, although that just be my selected seat of learning.
Very best of luck
Alasdair

Also don't be disheartened if you only get 60% for what you thought was a good essay, apparently thats how they mark post grad, although that just be my selected seat of learning.
Very best of luck
Alasdair