My response is based on getting there on public transport as I don't drive yet (soon!).
It actually took me over 2 hours to get back on the night buses from Chiswick on Saturday. For me, it's also a question of safety - I got stuck in Peckham at 2.45 on Sunday morning as the night bus terminated early. It's my one golden rule about travelling in London - I don't get stuck in Peckham at night, it's bl00dy dangerous.
Therefore, I'm not going to Chiswick again till I can either drive myself or scrounge a lift! Will just go to Hammersmith and treat myself to a cab back (therefore can only afford to do it once a month) or Greenwich for freestyling.