Heathrow flight at 6:00AM!!

Which terminal?

I recently used the newish Premier Inn at T4 (access to the terminal via a walkway) for an early flight from that Terminal. It worked well.

Yes, stay overnight at LHR. Sofitel is in Terminal 5, convenient and very nice, excellent restaurant.
Never let a cruise ship or tour company book your flights! I have heard so many situations like yours when the tour company/cruise booked horrible flight times and connections for their clients.

Thank you both! Yes, live and learn regarding cruise companies and flight :-(.

Katy, I believe we will be at Terminal 2 ? (Swissair Int'l).
Oh, another question - how EARLY should we plan on being at the airport for said 6:00AM flight?

Suggested time to get to the airport is 3 hours before scheduled departure. Depending on which terminal, what day of the week, and the mood of the security staff, I wouldn't cut it any closer unless I was in business or first class where you get to go through shorter quicker security lanes. I have never needed the full 3 hours, but it is more relaxing to not have to worry when you have extra time.

I always book myself a hotel room close to LHR unless I have a late afternoon flight. Several hotels are actually connected to a terminal now. Maybe not exactly the terminal you need, but close enough as you can take the underground to the other terminals.

There also is the Hoppa Bus service for around £5 that goes from most of the hotel front doors near the airport to all of the terminals (they can be very crowded, so plan for maybe missing one bus and having to take a later one) but don't run before 04:00 in the morning so might not be early enough for your 06:00 flight. The city buses are also free to and from the airport to the close by hotels but once again might not run early enough. The Tube does run round the clock many nights now, you would have to check to see if the one you need runs early enough and if it goes all the way to the airport at the time you will be needing it.

You need to find out what time the check in counter for the flight opens if you are dropping off bags. It won't do you any good to be at the airport at 3 am if the counter doesnt open til 430 or 5am.

As its a European flight its usually recommended to be there 2 hours prior to departure. I'm off skiing to Bulgaria next week, and the last check in time with my airline (BA) is 45 minutes prior to departure. Its also an early morning flight (8am) and being pretty risk adverse, I'm staying the night before at the airport and will aim to check-in by about 90 minutes before departure time. My experience Heathrow's not so busy first thing. Best to check your airlines website to be sure of timings.
Katy

Parts of Heathrow are busy at 5am as people head out on business.

The only public transport to Heathrow from Central London during the week overnight is the night bus (N9). Through Friday and Saturday night the tube runs out every 10 minutes to Terminals 2,3 and on to 5 (but not 4).

I would stay at the airport, Sofitel or one of the others directly at the airport to minimize agita. They will be able to tell you the quickest way to Terminal 2. I believe 2 hours is the recommended time to allow before the flight, but that was really more than enough for my recent 7AM flight out of Vienna. I have stayed at the Terminal 5 Sofitel a few times. There is a Marks and Spencer right outside the entrance to pick up a sandwich, wine, etc. if you do not want to eat "out" in the terminal.