Pull a 3 core cable through with the existing 2 core & wire it with a switched live?
I think I'd have to chase a new cable in. Also, I can't see how that'd help if the fan won't work with the L jumpered to the T. But I know very little about this stuff.
I have an extractor fan that I fitted in the bathroom many years ago.
It has an isolator, and a switch to turn it on and off.
Running to the fan itself are two wires, Live and Neutral, in a single cable.
This is relevant because I have bought a new fan, wired it up, and whilst it emits a faint hum it doesn't actually do anything.
I've got Live and Neutral (and an unused Earth) running to the fan, the instructions say it needs Live, Neutral and Switched Live.
I tried using a small jumper to connect the live to the switched live, but nothing happened.
How do I make the extractor extract?