Nice idea mate, but doesn't quite work like that. KIT days are used during the Maternity Leave so that the woman (or man in this day and age) can return to work to reintroduce themselves into the workplace. As previously, if you returned to work even for a day it affected your maternity pay/periods...
Also guys, please remember that if your partner does not intend to return to work, then they still need to abide by their normal notice period (for most people 1 month). Which means if they only tell their employer on the day they are due to return then they need to serve a months notice.
Other things to consider are asking for part time or flexible working hours. Under employment law your partner/wife has the right to ask for this and for the employer to consider this. But this can very much depend on the type of job, expected working hours etc etc. If it is of business detriment to allow this, then they can refuse.
Always happy to help with stuff like this,
Andy