I had the sunroof drain problem too. I tried to shove something down the tube but it just got even more jammed.
I found a solution which worked well.
You can access the tube that connects to the holes in the front corners of the sunroof if you:
1) Take off the rubber seal around the top of the door (just a press fit).
2) Remove the handle in the roof of the car over the drivers / passengers head.
3) Remove the sun-visor.
4) Slightly pull away (towards the other side of the car, not downwards) the cover which is over the column between door and windscreen.
5) Get a little access under the roof lining to find the white rubber tube that carries drain water from the sunroof down the column to the floor outside the car.
6) Pulling that rubber tube off the drain hole (make sure you have mopped up the standing water!) and stick it over the nozzle of a foot-pump.
7) Blast any blockage out with ease
While you have the door seal off you can also remove the winscreen seal on that edge and make sure the drain hole is clear down there.