<<<<<Assuming that you have working WiFi in each of your buildings;>>>>>>>>
You could avoid all the hassle of getting licenses from OfCom, and avoid paying fees for frequency coordination.
Look at WiFi "radios" with a HT form factor.
These HTs communicate thru the already existing WiFi network.
The Icom IP100H is one example, there are other similar units available from Kenwood, Yaesu, Tait.
These "radios" look, talk and feel to users like walkie-talkies.
There are several advantages here:
1) you won't need to buy any repeaters.
<<<<< The units will use the WiFi infrastructure that is already in place.>>>>>>
2) you can standardize on ONE version of HT that will work in all buildings,
3) This will allow buying in large lots, which will reduce your per unit cost
4) if a unit is lost, stolen, or broken, another identical unit can be shared from another building
5) the same units can go back and forth between buildings WITHOUT reprogramming,
6) you can program several different talk groups in each each radio
7) each building can have its own group, or
8) you can program an "all call group", so that all workers can be reached at once, or
9) workers from one building can contact workers in another building directly,
10) you can program other talkgroups (Admin, Security, Food service, Medical, etc) into the same model radio,
so that these various separate groups can talk amongst themselves without impinging on other groups communications,
11) putting all the talk groups in every radio will allow the different groups to talk to each other in emergencies.
12) privacy of coomunications will be enhanced, because the signals are not going out of the building
Several caveats here:
1) there must be WiFi coverage in all areas of the buildings where you want to use the HTs.
to insure complete coverage, Wireless Access Points may need to be installed in areas where they normally wouldn't be
2) Wifi Router must have Uninteruptible Power Supplies.
3) Each buildings WiFi must be connected to the internet to allow inter building communications.
Questions?
PM me here on RR.