[quote user="ranjeetrain"][quote user="JoelSim"]Will my tuner plug into the rooftop TV aerial?[/quote]
Yes. So long as the impedance matches, which in most likelihood will. Luckily for us, both TV and Radio antennas have same impedance. 75 ohms.[/quote]
And as long as your radio comes from the same transmitter, or at least the same direction, as the TV. FM actually requires a rather different antenna to TV, and digital radio a similar aerial to TV but with vertically polarisation rather than the horizontal usually required for TV, but any rooftop antenna will work as a crude omnidirectional for FM radio and/or DAB, and will almost certainly be better than the wire T you're using at the moment.
(FYI, the roof here at home has a Sky dish, a TV aerial, and separate FM and DAB antennae, but I wouldn't suggest you go that far!)