Well, I started my first flare in mid-November 2008 when my son was about four weeks old and wasn't diagnosed until the end of January. I did have a couple of weeks in December when my symptoms eased a lot, though. I'm not going to lie...it was really, really, really hard. I was really sick (urgent diarrhea 15-20 times a day at my worst), I lost my milk supply (that was really disappointing), and my husband had to take on a lot of the burden of keeping the house running and taking care of our son because I couldn't. We also live across the country from our family, so didn't have help readily available.
However, since you know you have UC, you can be really aggressive at treating it if you start to flare after the baby is born. Also, I was horribly disappointed when I lost my supply when my son was 8 weeks old, but, he's perfectly happy and healthy as a formula-fed baby. I guess what I'm saying is that if you plan to breastfeed, but have to quit in order to get yourself healthy, then do it. You, your baby, and the rest of your family will be much better off if you feel good than if you feel bad and continue to breasfeed.
Good luck and congrats!! You're almost there!
Symptoms began in November 2008, ~4 weeks after giving birth to my son.
Eased for ~3 weeks in December, possibly b/c of probiotic use?
Returned in January 2009 (with a vengeance), diagnosed with pancolitis on January 30.
Currently taking Asacol (400mg 4 pills 3x daily), Rowasa nightly,
40mg 30mg 20mg 15mg 10mg 10mg of Prednisone every other day, Culturelle probiotic, and Zoloft (25 mg).