Reading between the lines a bit here, I take it you’d like to take over the installation? I’m not too fussed over it, I just want it done - my plan was to get the generic stuff cheap from eBay to save a few bob compared to the official site hence not specifying connectors and fittings in my original draft to the board.
By all means do it as you see fit but as a handover of sorts my idea was to use steel cable, and suspend a wire between the walls in the vestibule (outside wall and inner wall) then hang off that wire a wire for each 1m section of pipe using jubilee clips to hold each section in place. The fan can be mounted to the wall using a wooden bracket as it’s a bit heavier, with steel wire as a backup in case of fire. There are numerous fittings used with steel wire, which allow for a hook to be used in the walls and ceilings and then a crimp to make a loop out of the wire. There is also a thing to tighten up the cables without twisting them so everything can be made level.
I originally planned for this to go over the main door but if we do that it must not block the fire exit in the event of a fire so everything must be done correctly such as using fire rated wall plugs as plastic ones will just melt and cause the ventilation to fall down, possibly blocking the exit. If you don’t want to do it that way, you can put it over the classroom but then you’ll want to have to go further into the space due to the angle of the wall and may benefit from another metre of 100mm pipe. Remember, my proposal I gave to the board was only the first step to get fresh air into the space - once things have settled a bit I will be drafting another proposal for distributing fresh air around better. Don’t forget to use the fire damper too - this seals off if it gets hot and prevent the fan fueling a fire by blowing fresh air in. Maybe have a look online and get familiar with the regulations which aren’t always too clear, but it is required.
I also have in an eBay basket some 100mm covers for the pipe with fly guards, one for outside and one for inside. Stops crud getting in so easily and has a nice finish. Again, cheap from eBay as it’s super generic.
In terms of mounting the ventilation system, it would be the same. Suspended on steel wire would reduce any vibration and would be similar to the official mounting kit that was an optional extra but at considerable cost. Just make sure you get a steel wire capable of holding the unit’s weight.
I’m sure you’ll do great so I’ll leave it with you