... a bit Suffolk
Where to put the kit? Building the equipment into fixed cabinets or shelving seems like a good idea. It looks ORGANISED. It's also difficult to get at the kit to fault find, even more difficult to move the kit to another station, and the operator has no control over how they work. PUT THE KIT ON A TROLLEY. It solves these problems and abandoned lunches, felt tip pens, reels of masking tape, newspaper, mutton cloth, and "stuff" doesn't flood the place quite so quickly.
Use a computer trolley. It should have a top surface for the PC and monitor and ideally a retractable drawer for the keyboard with a sliding mouse shelf that can be set either left or right handed. (Though it is just about possible to squeeze a mini-tower PC and a monitor on to the top of one these trolleys, you are better off with a PC in a desk top case.) The trolley should have a lower shelf, usually called a "printer" shelf, for the power amp and mike pre-amp. (Mounting the power amp here lowers the centre of gravity.) If the printer shelf slides stop it sliding with a self tapping screw.
Mount a four way mains distribution strip on the trolley to plug everything in. Use a distribution strip with an on/off switch so everything can be switched off in one action.
A useful tweak is to fix a medium sized speaker frame (basket) to the trolley. It makes a very useful place to wind long leads out of the way before moving the trolley.
Think before putting the monitor up on a shelf in front of the operator. It may seem easier for the operator if the monitor is in front of them but looking up soon puts a crick in the neck. It is easier to turn ninety degrees and look down at a monitor on a trolley.
Think even longer before putting the monitor on a triangular shelf in a cabin corner. Monitor and TV manufacturers are very skilled at making their products looking smaller and sleeker than they are and you will be surprised how big your shelf will have to be.