Dead Man's Shoes (2004) is mentioned in his wiki page as being inspired by events from his childhood.
This Is England (2006) is semi-autobiographical, in one of those 'director talks before the film' thingies he said that Turgoos' character was based on him at around that age, can't find a source online for that though. Perhaps it's in the extras or something.
Peter Mullan's wiki describes involvement in gangs similar to those in his film Neds (2010)
Not added as these are perhaps only 'inspired by' rather than 'based' on chldhood/teenage events, depends where you're drawing the line.
American Graffiti (1973) seems a better fit though.
The genesis of American Graffiti was in Lucas' own teenage years in early 1960s Modesto. -link