Yes it's doable.
I started my first year at uni doing BA Joint Honours French/TESOL in Sept 04.
In Jan 05 I found out I was pregnant.
I finished the year in June, but had to in for resit exams in August because I failed one of my modules.
Because I was so heavily pregnant I was able to sit my exam in the Special Circumstances room - they gave me an orthopoedic (sp?) chair and allowed me to take breaks and have short walks about if I was uncomfortable.
I had my baby in Sept 05, and took a year out of uni to be a mama.
Then after a year I felt ready to go back to uni, but because I was previously doing a joint honours language course, it would have involved me taking spending a year in France. This would have been impractical with a baby, so I decided to switch courses.
So in Sept 06 I started afresh from first year again doing BA Single Honours Classical Civilisation.
My mother babysits my daughter whilst I'm in classes. (You could always opt for a creche though - if you are a full time student and you use a creche or a registered childminder for your children, the government pays 80% of the cost of childcare.)
I am pregnant with baby number 2, so when I do my Summer exams again I will be sitting them in the Special Circ room with the nice comfy chair
This baby is due in July, so I'm going to take next year out again, and then return to second year Classics in Sept 08. By that time my eldest will be 3 and my youngest will be 1.
It's hard work, no doubt about it, but it's definitely doable
Good luck!