Hiya @NK2020 (Nad)
In my eyes even students letting a property is still classed just like a HMO and in the Cuckoo Terms & Conditions it does state “Residential Services” not Business.
Im sure even BT Superfast 1 is equivalent to being only for Residential Use eg…a family of 4 compared to 5 Tenants sharing a house having individual room numbers just like a HMO which should require business services to be provided for better reliability…its a grey area and that saying I have seen a similar situation on here where a house share or student let had many Different Routers from different providers connecting to Individual Lines & Sockets.
Now with regards to that I’ll leave this thread open for the Cuckoo Team to respond on that point.
However the Other Questions I dont mind answering.
A Gigabit Switch is basically an Ethernet Splitter where it takes 1-4 ethernet ports from an Input Source eg…a Modem Only or Modem/Router and allows multiple ethernet wires to be connected to it cutting out the need for wireless devices back to the source to obtain Individual Device IP numbers on the network which is normally a maximum of 254 devices but just bare in mind the more devices trying to get a piece of the connection speed at any one time for example a 50mb connection (÷ 5/10 devices) the slower the internet will feel to that person so heavier use would require more speed.
Currently boosters or other router setups isnt something Cuckoo offer however with the right advice,the manufacturers website,Amazon UK or other third party tech websites such as ebuyer or broadband buyer just to name a few im sure you can find the tech you need but as a little
Tip :- TP Link do offer discount code links occasionally on there website via certain resellers however if that helps.
There are other newer systems called “MESH Routers” and what these do is the same thing as a switch but smaller & wirelessly over an ethernet cable.
You run the ethernet cable from the back of your Modem/Router to the point you want the mesh “node” normally 1-3 “Nodes” placed eg…the Master Bedroom or the 1st Floor Landing & The Second Floor then this “repeats” the signal from the router and creates a wireless point on the 1st floor so as you move from ground floor to first floor to second floor the signal remains quite strong depending on the Wireless frequency used 2.4GHZ Or 5GHZ this way the user shouldnt notice any speed drops like a teenager on a whatsapp video call for example and any dead spots in the property are then covered or you could have another “node” added later on.
The TP Link Archer model I use myself isn’t a mesh device (as i type this with a full signal on my 1st Floor) as I currently dont have the Mesh update but this is included in the newer models they have eg… Version 3 (V3).
But you can purchase a MESH Modem/Router yourself that does what the Cuckoo Router does and more then you just insert the Chosen Providers Connection Details into the setup pages on there menus either manually or selectable by a connection menu if that provider is built in by the web interface or via there App (if available) on a Mobile Device if supported for example.
I always recommend spending time on the Tech Providers Website to check that the specific models do what you looking for…TP Link do have a few tools that ask you questions to help you select the right model based on your requirements eg…are you a Virgin Media Customer or Openreach/BT/TALKTALK/SKY User so its worth doing that research as knowledge is power so they say. 
Having a Different Router Means Its also “Unlocked” so other Providers Connection Details can be used and its your property so when you end your contract you dont have to send the provider there tech back or have to be billed for keeping it as many providers now do to recycle or repurpose to keep there costs down.
Its just easier this way to add the new providers details on connection day to your existing Modem/Router and Press Connect (if still compatible and working correctly of course).
While Cuckoo hope as a Residential Customer you will be Happy and wont need to leave or transfer to another provider it could happen but I havent heard of anyone leaving after connecting just yet.
The Cuckoo Technicolor DWA0120 Router was designed as a business class of router rather than a Home User Modem/Router to be of a Higher Grade for less issues but with technology changing every day there will always be something better out before long…the community and the cuckoo team have contributed to allowing there users the freedom of obtaining your Connection Details from the team directly & more recently the Awesome Web Team that I dont praise half as much as i should (do i @afenton90
& @Insung
) for integrating this into each customers online account menus.
Hope This Helps.