East Dulwich is a lovely place (although beware the distance between E.Dulwich station and many of the houses advertised as being in East Dulwich - the station is at one end of a big area), with plenty of parks, cafes, etc, but it might be a little on the grown-up (ie dull) side for you. (not to criticise East Dulwich - i lived there when i was 24/25 for 6 months before moving to Brixton. I moved back when i had kids). Depends a bit on where you will be socialising - if you'll be heading Central/East for nightlife you might want to be closer to the E.London Line (New Cross?). Might also be worth looking around Denmark Hill for the direct trains to Eltham - Dog Kennel Hill side of E.Dulwich gets you better station access, so less buses, and edgier Camberwell bars as well as Lordship Lane's nappy valley
