I was worried about this too (I am half way through a 6 month contract with leave entitlements). The counsellor at Monash IVF told us we will be given certificates for the days around OPU. If you didn't tell your manager you were undergoing IVF treatment they would have to pay you SL based on the certificates anyway.
I had a chat with my manager about it and she said I would be able to use sick leave for it and she is also fine with me going to my appointments and leaving it up to me whether I make up the time or get short paid/take leave etc.
There is a lot to be said for Managers who try to do the right thing by staff.