I managed to get the GIRO forms from the post office - now on to the second step, which is how to get them processed. The bank isn't very sure, but I have a very helpful officer who is trying to find out for me. You would think GIRO would pretty much be second nature though, considering how many organisations use GIRO.
Thanks to everyone who sent us GIRO forms! It's really great to see people respond to our GIRO appeal.