yup... and got the t-shirt. currently wearing the t shirt. my back is bloody aweful. between waking with dd and my back, the last 2 weeks i've had on average 2 hours sleep tops...
but, as for not getting back to sleep once woken with your baby, you will! i was SO tired i would fall asleep as soon as my head hit the pillow. I didnt know tiredness like it in the bginning. but i got used to it.
In the first few months, at the least, you really will be able to get up, feed, go back to sleep
Have you thought about doing the continum method ( shown on bringing up baby) ? I wish i'd known about it before i had Dd.( now 9 months )
the sling would have saved alot of my back ache, ironically as it hold the baby so close and your back is really supported. Also, the not having to get up and down, would have helped things a lot too... as my back would have had far more rest over night. I now sleep with her for this reason, and wish we'd done it sooner as i get ,and so does she, alot more sleep. She happily sleeps on her own in her cot in the daytime.
maybe you could look into it abit more before you have your baby?
failing that... you always have MN to entertain you in the small hours!