The midwife brought her own kit and told me to buy cheap shower curtains (paid £2.99 in Tesco) and cheap bedding (I bought a single duvet and pillow from Tesco for very little).
I also got one of those big balls from freecycle which was really useful.
Then things for the baby - blankets, nappies, vests, babygro, cardigan. This was all in a bag in case we had to transfer to hospital. I also packed another bag for me for hospital just in case (clothes, book, old pants, jumbo maternity pads, chocolate, money, phone)
Food - for me, and husband and midwives.
Old blankets and towels.
I think that's all.
In terms of how I prepared, I spent a lot of time cooking soups and cakes and stashing them in the freezer. This was very useful later.... And making lots of different plans based on different scenarios to ensure the older DC were looked after.
Hope that helps and best of luck to you