Could someone advise me please, I have visited a premise which has a server installation for the computer systems etc, about the same size as a single wardrobe. It has a secure door etc but it is in a store room with various items such as boxes, foldable chairs etc. There is no air-conditioning in the room either. Is this a problem?  

How warm was the room when you went in? Environmental controls are primarily to stop damage to the server, although it is an ignition source and if it's not installed to spec (e.g. manufacturer requires an air con environment) there is a risk. Too hot and you break it, too hot and you may have a fire.

A dedicated room is usually preferred and storage should be minimised.