That’s a fascinating idea. Are ONT’s capable of POE? (Which, to the best of my knowledge, does not go into the dc power socket but requires a compatible RJ45 port. I could be wrong there, as I’ve been retired a few years now. Certainly, I’ve never seen one that splits off to the dc power connector).
Edit: Indeed, you would appear to be correct. That's extremely useful info for the future.
You say there is a Hyperoptic socket.
Seems Hyperoptic locked out any other fibre network providers for your building. This means you have to use Hyperoptic for your fibre connection.
You will still need a power socket near your Hyperoptic socket though to power their hub. You can then send connections to any of the other sockets, depending on the number of spare LAN ports on their router.
As the output from the ONT is ethernet, you can have up to 100m between the ONT and the router. You just need to run some cat 5e or 6 between the two.
As WSH said, depending on where you want to place the hub, use a short length of Cat5e or Cat6 to place between the Hyperoptic socket and another numbered socket, then connect up the hub in the corresponding room.
Find a local electrician who is prepared to fit you in when it's convenient for them. There are at least two different ways of getting a usable socket fitted in the cupboard that are only going to take a good electrician 10-15 minutes to do. Neither will be the tidiest in the world but it can be done. One involves a feed from the fusebox, the other more controversially would involve a switched 6A max spur from the lighting circuit in the cupboard (I believe this is still within code!).
I use a TP-Link PoE Splitter for the ONT, bought from amazon, fed from a POE switch and it supports GigE.
I have a UPS in another part of the house, so it allowed me to connect the UPS to the ONT via Cat5E.
The supplied power plug is the size required for the ONT.
The building recently got cabled by Openreach as well, and in the cupboard outside the flat there is the Openreach junction box, so I believe that’s not a problem. It’s quite weird though that they placed the Hyperoptic socket in the cupboard, where there is no electricity. I wonder if this flat ever had the Hyperoptic broadband connected.
I just opened one of the numbered phone sockets and this is what they look like, do you reckon those cables would support electricity through them, or would it need a normal CAT5e cable fitted?
I wish I was an electrician, fitting a power outlet is indeed a very easy job, it’s finding an electrician that’s difficult!