Congratulations! I totally understand what you mean about being tired during the day and not sleeping well at night. A friend of mine recommended a homeopathic/natural sleep aid that's safe to use during pregnancy. I'd check with your midwife or pharmacist to see what they recommend. As for being stressed about what's to come, I hear that, too. I have OCD, and I feel incredibly anxious when I feel unprepared or don't have plans, back-up plans, etc.
What helps me is making lists and budgets. Budgets of how much the baby gear will cost (and I spend time researching the best deals online) and how much I anticipate the baby will cost once it's born (not much for the first 6 months or so, really, unless you use formula or child care). And the lists are what things I need to do to get ready for baby and an approximate timeline (install car seat, wash clothes, make food ahead for the freezer; buy baby nosal saline spray, baby pain medicine, child thermometer, etc.), and what things I need to pack for the hospital.
As for getting ready for labor, which looms large, as soon as I feel ready, I start reading positive birth stories. "Ina May's Guide to Childbirth" is a classic in natural birth circles. The first half of the book is birth stories from different women, and the second half is Ina May's more technical information about the various aspects of birth, and how "The Farm" handles them and achieves such great outcomes (happy mums, healthy babies, and very low c-section/transfer rates). Keep in mind this book is extremely "crunchy", so you may or may not have a hard time relating to individual stories, but when you put them all together, you'll see a wide range of birth experiences and get great confidence about what our bodies can do. Then you can move on to more practical birth guides, like Penny Simkin's "The Birth Partner" (my hands-down favorite birth book), which details how to prepare for birth, how to get through natural birth, and how to make choices about the kind of birth you want (with even-handed charts of pros and cons and non-judgmental presentation of options).
And watch some natural birth videos on YouTube. Watch some gentle/family-centered c-section videos, too (they can be harder to find, as cameras aren't often allowed in surgical theater). And definitely like the Facebook page "Birth Without Fear" and follow their blog. Every day, they present honest, empowering, non-judgmental images and stories of birth. They support all women and all types of birth. It's the most supportive online community I've found for birth.
As for how you'll take care of this baby once it's born, you really just inure that out as you to along. Hopefully you have a friend or two or family member with kids that you can be honest with about what's going on and how you're coping. You need a friend who asks about you first and baby second. A friend who doesn't expect that everything out of your mouth will be about how beautiful your baby is and how amazing motherhood is. You need to be able to talk about sore nipples, and achy crotch, and lack of sleep, and spit-up all over your clothes, and having a baby who wants to be held all the time, even when you need to go to the bathroom. A friend who understands that the best 10 minutes of your day in those first few weeks are your time in the shower by yourself massaging your engorged boobs to release the pressure of so much milk and not having to e responsible for anyone but yourself. In fact, I suggest you take one of those showers in the morning and one again at night.
And if that last bit about newborns sounds overwhelming, don't be scared. For the first few weeks, they sleep 20 hours a day. Feeding them every two hours and sometimes not being able to figure out why they're crying is exhausting, for sure, but nature gives you and baby time to figure things out together. You don't wake up instantly with a 6-month-old that you need to transition to solids and who is teething. It all happens gradually, and you work it out as you go. Be prepared to roll with it, as newborns change every couple of weeks and you need to be able to pay attention and adjust accordingly. A great encyclopedia of baby development that will help you understand what your baby is going through and troubleshoot any problems from birth to age two is Dr. Sears's "The Baby Book".
And if you start preparing yourself and you find yourself more anxious or overwhelmed than feels "right", please do talk to your carer. Hormones heighten emotions and sometimes you need a bit of extra help from a professional. Please be sure to take care of yourself! All the best.