There are a couple of apps on market to do this.
Tasker (I haven't used but some on here swear by it)
Juice defender - used it for about a week, saved battery great but got cheesed off with the delay when waking the phone up and waiting for it to initialise the connections.
Sometimes seemed to take ages.
So I ditched it.
Oh Juice defender can't change widgets or homescreens but does do the wifi and mobile data depending on time and/or location.

Hope that helps.

 

Timed settings are easy. If you just want to change things like volume, WiFi, bluetooth, brightness at certain times/days then a simple app like Timeriffic will do it.

If you want to control almost all aspects of the phone as a function of time, location, calendar, and are prepared to tackle a steeper learning curve, then Tasker is generally regarded as the most powerful tool. There are others as well.

I don't know about changing backgrounds and widgets to a schedule. HTC's Sense software offers things called "scenes" (or something like that), which are sets of homescreen settings (backgrounds and widgets). So by changing scene you can quickly swap things like this by hand - I can't remember whether you can schedule changes though (suspect not, but I've not used Sense for a long time so may be wrong). I also don't know whether a 3rd party app can change these to a schedule - as these are HTC things rather than general Android features they are less likely to be supported by a 3rd party app, but they might be. If so, I'm sure someone will tell us what app can do it.

 

You can't change the homescreens (widgets, icons etc...) automatically but you can just have 1 scene for Home and 1 for School and change them when you are in each environment. Thats built into the phone (no apps needed)

Hope this helps