I lived in London for ovcer 4 yrs. I have best of both worlds. Im orignally from Scotland and at the time of moving to London (2001) I was homeless and spent 3 1/2 yrs sorting my life out down there (and no i was never into drugs or drink). I managed to educate myself by doing a music and teaching course. I also managed to get my own place which I kept for 1-year and had no problems paying the rent. I even survived down there on the doll for 3years, so if anyone tells you that its highly expensive is talking rubbish. It's only the housing that is the main issue - which is a ridiculiously over priced, everything else apart from drinks and housing was exactly the same as Edinburgh. Overall I hated London but I learned soooo much from my experiences.
GOOD THINGS: I found that London was a 24hr city with a great buzz about it. Plenty of educational and work opportunities. Great night life if your into clubbing. Lots of things to do, you'll never get bored. Go see Camden Town and St Katherines Dock. Great place to go and experience if your in your 20s. It's like your in different towns when you go from place to place on the underground - all be it with the same arogent people.
BAD THINGS: No sense of community. I found the majority of people highly ignorent and rude. This is a major turn off. Transport system is a disgrace - the high population of course does not help. Commute time is looooooooong! You will find it hard to make new friends as people tend to keep themselves to themselves and stay within there own groups. BAD BAD place to bring up kids. High crime rate and you wont go short finding people offering you drugs on the street. Lots of homeless people - hence I was once but never actually slept on the streets. It's also way too fast paced. You can't relax!
Overall I hated London but gained a lot from it. The first 6-months were great but after that I hated the place. I only went down there to study music and follow my dreams and I did that
P.S. Plenty Ausies down there, I met two lovely ausies, who are now my best friends.