Unpaid Maternity means lower tax bracket?

Hi all,
My wife and I are both currently in the higher tax bracket. She is due to have a baby next year and is keen to take some extra unpaid maternity leave.
In relation to tax, depending on the amount of unpaid maternity she takes, she could fall into the lower tax bracket for the year.
Currently we are assessed separately.
What is the best thing to do in order to minimise our tax?
Would we benefit most if she took a lot of unpaid and I took all the tax credits? Or maybe better if she stayed in the higher bracket so she can claim back more on medical expenses at the end of the year?
Cheers.

If your wife will fall into the lower rate tax band next year as a result of unpaid leave and she is paying for private maternity care, why not pay the consultant fees in advance this year so she can claim the tax back this year at the higher rate? The disadvantage is that you end up paying the bill before you actually have to but you'll be able to claim more back. As far as I know there isn't any problem in doing this and I know of cases where it has been done.