As you head for the airport in London, I highly recommend having your taxi driver stop by Harvey Nics in Knightsbridge.  On the fifth floor, you can procure some bread from the mythic Parisian boulanger, Poilane which will still be fresh enough by the time you arrive home.  Nothing cures jetlag better than warm, buttered Poilane toast spread with marmelade and Fortnum and Mason tea.   

(As far as I know, the only place you can sample Poilane in L.A. is at the cafe at Saks, who have it flown in daily although I haven’t been in some time.)