Hello!
Why not check out our bookshop?
Midwifery Books and More
The most up to date versions I believe are really critical for the course. You wouldn't really be able to reference out of date publications incase the evidence has changed between publications. Why not have a look in the library etc before purchasing the more expensive books.. THat way you could get 2/3 of the recent ones you found really helpful instead of spending money on loads of second hand ones that might not have the current-best evidence.