As for the Birthday Song singing, we all know how Kai would be very excited once he laid his hands on his drum kit and start playing 'ride with the rockers' therefore we have to be faster then him. I was hoping that after they have gone from the stage (and checking the time that it's not past 10 yet), instead of saying 'Encore' as the tradition, we would start to sing 'Happy Birthday' in ENGLISH and just keep on repeating until Kai come out, and then we wil sing once more, and then finish.
About the balloons, I know that it was a bit of a silly idea and that it shouldn't relaly be done, considering the crew at Islington might not like us very much. Therefore, suggested by some others, I think Glowsticks would be great.
I know some people said about party poppers (if those are called that), but I don't feel they are the best, as they would create a huge amount of noise (causing screams from people) and that it would create a lot of rubbish. So I think glowsticks would be good.
(a quick suggestions, Cyberdogs does REAL REAL great glowsticks, I bought two for myself for the MUCC concert last time and it lasted to glow until the next day... so instead of some cheap and thin and weak ones, get those, they're only 1.50 pound! ^^)