Welcome to FT, emeybee!
Can you tell us more about your complete itinerary? What time do you arrive into Heathrow before the long layover? Where from? Which airline(s) are you flying? In what class(es)? Do you have one ticket for the entire journey, or two?
Similarly, on the way back, when do you get back from EBB to London? Are you staying in London overnight before you fly to LAX?