Probably a really silly question, but if your FM radio is portable, have you tried moving it around the house to see where you can get the best signal? You might find a sweet spot. Unfortunately, radio reception is also influenced by the weather so you still might get patchy reception...
If I was you BG I'd try and borrow a DAB radio and see if you can get Sussex on it first.
The thing with DAB, compared to FM, is that the signal is either received or not (pretty much). No fuzz or crackle around the edges as with FM that's teettering on the edge of good reception. DAB is...