Getting to Heathrow Airport

You have to be there two hours ahead and I doubt that metro is already going. It will be probably taxi.

I would stay at a hotel at the airport. I've stayed at the Holiday Inn Express and I took a taxi to the airport the next day.

I would also stay near the airport that last night. Taxi fare out to Heathrow will not be cheap. There are very nice hotels within a five minute taxi ride from the airport. I was really happy with the Premier Inn Terminal 5.

Neither the Heathrow Express nor the underground operate early enough to get you there in time, so your options are to stay nearby the night before or book a taxi when you get there. At that time of day, staying in a hotel at the airport will probably be cheaper.

Official check in advice for travelling to the States is 3 hours before departure.

Book a car service, around half the price of a normal (hackney) taxi:
http://www.tripadvisor.co.uk/ShowTopic-g186338-i17-k4886933-POLL_Airport_Car_Service-London_England.html

The public transport option from Kennington would be bus to Traflagar Square and then bus to Heathrow. Would take about an hour and a quarter at minimum and not really convenient.

When I asked this question on Tripadvisor, regarding getting to Heathrow from south of the Thames ( my area was Shad Thames), car service was highly recommended, with Blackberry cabs being the most recommended. Price was reputed to be around £35 but I did not check, as we ended up using Tube + Heathrow Express (not an option for you, however).

Blacklane.com also offers PRIVATE car service in London. You can go to their site, put in your information and they will respond with a pre-arranged price. They are very reputable.

We always stay at a hotel near LHR the night before our early flights back to the US. You can enjoy a last day in Lodnon without worrying about getting to Heathrow in the early morning hours. WE use the Travelodge chain, sign in on their website, travelodge.co.uk, and get some really reduced rates, especially around LHR. We like Heathrow Travelodge Central, which isn't central at all, but is in a little neighborhood with a pizza place, an authentic Polish deli and market, pubs, fast food, etc. Most other LHR hotels have no options nearby and one is forced to eat the mundane hotel selections. We usually get a nice room for around 29 GBP on their special bargain sales. There is a Hoppa bus that starts at 0430 and stops at all of the hotels. It will get you to LHR in plenty of time. Staying near LHR takes all the worry out of a flight home since you are just minutes from the terminal and not fretting about getting to LHR from some distance away, not to mention the cost of a car service. Works for us.

We always stay at a hotel near LHR the night before our early flights back to the US. You can enjoy a last day in Lodnon without worrying about getting to Heathrow in the early morning hours. WE use the Travelodge chain, sign in on their website, travelodge.co.uk, and get some really reduced rates, especially around LHR. We like Heathrow Travelodge Central, which isn't central at all, but is in a little neighborhood with a pizza place, an authentic Polish deli and market, pubs, fast food, etc. Most other LHR hotels have no options nearby and one is forced to eat the mundane hotel selections. We usually get a nice room for around 29 GBP on their special bargain sales. There is a Hoppa bus that starts at 0430 and stops at all of the hotels. It will get you to LHR in plenty of time. Staying near LHR takes all the worry out of a flight home since you are just minutes from the terminal and not fretting about getting to LHR from some distance away, not to mention the cost of a car service. Works for us.

I'll just had my vote for staying at a Heathrow hotel - that's what we did last year before an early morning flight. Much less stressful for me. We stayed at the Ibis, small rooms but adequate and the staff was very helpful.