Oh man, i really want to go to Supersonic. Swans, Melt Banana and Napalm Death? Mmmhmm.
If you do go mate, check out a band called Bong and let me know what you think. They are really slow, Sleep-inspired, psychedelic, stoner/doom kinda stuff. I've been going to see them do the rounRAB in the pubs and clubs in Newcastle for a few years now.