Of course you can live in London on 30K!!! Millions do for fucks sake.
You wont be living in Chelsea, Fulham or Clapham, forget hip hang outs like Shoreditch and Peckham, but lots of places in your budget, on 30K thats about a 1K a month , anything above that you'll struggle to convince estate agents to take you on.
You can look in Crystal Palace, in the South which actually has lots of young middle class people and hang outs of bars and cafes.
You can look in outer suburbs in South East London places like Bromley or over west London like Hayes, which may be a bit boring, but are safe.
There are a lot of social housing controlled rents you can apply for in London, you will qualify for the below for example in hip West Norwood which has lots of coffee bars and cool pubs and restaurants and farmers food market.
www.rightmove.co.uk/properties/128978840#/?channel=RES_LET
But if you use your £1000 a month budget to a flat share in a large house, altough not ideal, you can live pretty much anywhere , even uber posh and central Marylebone. I know this as my friend lives there in a flat share found through a normal estate agent, so no mates rates.
Lastly there are guardian angel options , where you live in a flat on token rent in a disused police station , etc awaiting development. They are full of artists and creative people and safe and cheap way to live in a good area.