I have a flight at 6:20 am from Heathrow Terminal 4. I usually take the 285 into Heathrow, then either walk or get the free transfer train to my terminal.
Terminal 4 requires a free transfer train, but this only starts at 5 am in the morning.
My navigation app suggests the 555 bus but this only runs every hour and doesn’t start that early in the morning, so that option doesn’t work for me.
How does one get from Heathrow Central Bus Station to Terminal 4 at around 3:30 am?