Heya mutch, welcome to Amiga.org! I'm sorry to say I also get this problem with Grapevine on my A600, and I'm not sure if there's any way around it.
It certainly would be nice to get the source code for Grapevine, I think it's a great little IRC program and it deserves to have a little more added and fixed.
As for some good Amiga IRC channels, here are the ones I go to:
irc.amigaworld.net #AmigaWorld
irc.efnet.net #Amiga
irc.freenode.net ##Amiga
irc.ecs.soton.ac.uk #Amiga
irc.superhosts.net #Team*AMIGA
