Sounds good but check out the garage re the possible master socket. If it is there, as long as there is a short cable from that to the insides of the hall socket all is well with my suggestion re disconnecting the hall to lounge cable. (I've just put a warning re that in the post about that disconnection).
Also if that is the location of the master, it doesn't matter how old or new it is, still disconnect the bell wire on T3. As you will be opening both sockets you may as well do it at both ends.
To get rid of the dangly filter in the hall, if it is not a master and the master is in the garage, you need an XTF68 or XTF 85, probably the 85, to replace the hall socket. The difference between them is the millimetre dimensions of the box. You will also need a Krone/IDC punchdown tool to connect the wires to the internals. Cheapo ones at similar prices from Maplin, B & Q etc.
You can legally do that. But that can be done when convenient.
Good luck on Monday .