You are right to feel apprehensive! Having a child, any child, is a huge undertaking and I wish more people considered all the ins and outs of pregnancy, childbirth and being a parent for the rest of your life.
You will be very tired. What can you do now to make your life easier for the first year?
Make a little surprise toy box (I did with all sorts of bits from the charity shop) and pick one out for your older child for when breastfeeding. Similarly, get a stash of new books to read to your older child when nursing at another point in the day.
Beg borrow or steal one of those bath cradles which leave your hands free to have both in bath at same time. Same with a wrap/carrier/double buggy.
Plan for an easy birth. Plan for a traumatic birth. Get help on your side. Book a cleaner to come weekly for the first two months. Stock freezer with freezer meals and good quality ready meals.
I had a friend have a worse second birth than her first. I had an 'easy' second birth but baby came with such speed and force the pain and chaos of an unmedicated, precipitous labour haunted me for months.
Baby then had sepsis at 3 weeks old. Back to hospital we went. That set me back. I did not sleep for three days and once discharged I couldn't get back 'up to speed'.
All the help was SO useful.