I will need to put up an aerial suitable for DTT of course. I see that with
the TV channels there are also radio channels including the ones I listen
to, BBC radio 3 and 4. I'm wondering if I should take down the FM aerial,
replace it with my DTT aerial, then can I just take the audio signal out of
my Freeview box and plug it into my amplifier in my living room and thus
get radio as good as the rather excellent FM I am used to?

Stick with the FM .. I do!...

If I did that I would cut off the FM signal to my Tivoli radio, I'm
wondering if the digital signal from the DTT aerial for radio is the same
as that for digital radio and could I change my Tivoli FM radio to a
Digital Tivoli radio and give it the signal from the DTT aerial on the
roof?




I bet it's not as simple as that.

No its not..

Alternatively I could keep the FM aerial on the mast and add the DTT
aerial. But can I send the digital signal down the same co-ax as the FM
signal? Will the different signals interfere in any way?

Can be done with a diplexer but sometimes separate leads are a better
bet. A lot depends also on where you live and what the digital TV signal
is like in terms of strength etc..

--
Tony Sayer