Just going to brainstorm a few considerations, in no particular order. Sorry for the random order of my thoughts!
If a few keys go missing on a desktop keyboard, it's £10 to get a new keyboard and 30 seconds to swap them. If they go missing on a laptop, it's £40 plus the time for a technician to take apart the laptop to replace it.
Consider the cost of storing the laptops. Cabinets that hold 30 laptops securely are not cheap. Also look at who has the keys to each cabinet, who checks each cabinet e.g. at the end of every day to ensure that the laptops are all switched off, all plugged in and that the cabinet is plugged in and charging.
Get a cabinet with a timer so that the laptops aren't being charged all of the time (can kill their batteries if they're always charging 24/7).
Consider where in each room the cabinet will go. They are not small and require an accessible plug, and a route for large groups of students to be able to fight to try and get a laptop at the same time.
Take a look at the profiles for all of your staff & students. Are they local, roaming, mandatory? Small enough for a class of 25-30 to be able to simultaneously download them on to laptops off the same wireless access point?
Can your wireless infrastructure cope with the increased load of everyone logging on, browsing the internet and even the basic machine polling done by servers all over the wireless rather than some being wired?
To end this long post - good luck!
EDIT: A final consideration. Never underestimate how long it takes to put 30 chargers and laptops into a cabinet. Set aside at least an hour to 2 hours per cabinet for wiring, setting the timer etc.