sounds daft but follow your heart, would it really be so bad if you did put your degree on hold for a while and finished it with OU when you had more time to do it? would you be able to afford for you to do 2.5 days a week.....
btw Tescos and all the major supermarkets are crying out for mothers who can do limited hours because of their family commitments, if you can do a couple of evenings a week you could easily get work at a superstore, if you don't mind the work, it's a bit monatomous, but sociable, not badly paid and fits around the family....and you might even be able to fit in study on top of it, if you so choose (btw I did 18 months of evenings shifts at Tescos and they were more than flexible)...good luck