Bit late, but for future reference, the way I always do it is to get the shuttle bus from the airport (used to be free) to Luton Airport Parkway then the train straight to West Hampstead and change to the overland. Really easy and no messing about.The trains from Luton Airport Parkway to West Hampstead run more or less 24 hours, so worst case scenario, if you miss the last Overground, you can get a cab from West Hampstead to Acton.
Sarah Harris ● 4875d