I think you can totally do it. If you were a student brand new to the OU so had to learn the system I'd say no but actually you'll be fine.
My top tips:
Make friends with your tutor from day 1 or from the day you get their phone number. I suppose it is unlikely you'll get to tutorials with a newborn so phone support will be vital for you.
Make use of the module facebook groups if that is your thing, I am very pro them but I know some aren't.
When you get access to both websites write down all your deadlines and rejig them in a different order if they are not chronological already (mine last year were not). Also any that are due in on the same day shift at least a week apart.
Aim to be ahead on the basis if you're ever working on time to the calendar you're doing well.
Set aside at least one night a week where you do no OU stuff not even read a facebook post.
Remember that it is 9 months of hard stress but you will get a break come june.
Do not underestimate the birth you may have or the baby you may have. I was a clueless first timer so thought I would work during her naps or her strapped to me in a sling. Ha.Ha.Ha.
Reaslistically I ended up with a traumatic birth and a baby with reflux who didnt sleep for a year so it did not work that way. I relied on family helping me out when they could.
If baby due Nov, I'd seriously try and think about getting the first two tmas for each course in before baby gets here. You'd do this by doing the reading first (do you have your course mats already? if so start now) then on the day your course sites open and you see your assignments you can start them. The first are usually shorter anyway. You won't be allowed them marked and returned before the deadline of course but to know they are in will be a weight off. There is usually two weeks off written into the course calendar for Christmas too. Presumably you won't be partying that much this year so use that time too.
It is hard but the pros are getting finished that year quicker and I just imagined myself in my graduation gear and how proud my daughter will be of me one day and it got me through.