Wet headlining :(

[Niall]

Have you cleared the sunroof drainage channels. There's a hole on either side that gets clogged with leaves and crap, shove an opened up coat hanger down there. This stopped the wet roof on my old xrdt.
As you said the other suspect is the aerial, it may need taking off and re-siliconing down

Careful doing that. They are only rubber pipes and mostly run inside the car so if you catch it with the end of the coat hanger, you could puncture it.
Got a compressor? Blow it out with a airline.