Hey mate, ive never seen afl games or nrl games available for download, however depending on where abouts you are in the uk you should be able to catch the games at a few pubs, especially the walkabout pubs. aussie pubs in and around london, i think there is about 4 in total. When i was over there they showed all the games, especially the big games finals and grand finals, they will draw a big crowd too with all the aussies and kiwis living in london. So yeah, just depends where your your gonna be.
Its actually suprising a few of the guys on my contiki tour were even able to watch one of the afl semis live when we were in rome of all places, at one of the pubs there.