On our way back from Oslo, we had about a 5 hour layover in London. Instead of sitting around in the airport waiting for our next flight, we decided to get out and see the city. With only 5 hours, it was pretty tight, but we made it work.
If you find yourself with some extra time in Heathrow, here's what we did and some time saving tips!
1. Bags: Make sure that your bags are checked through to your final destination. Otherwise, you will have to waste precious time claiming your bags and rechecking them.
2. Getting through the Airport: Organize yourself before you get off the plane so that you can get through immigration and customs as quickly as possible. All you need to do at the border is let them know that you have a long layover and are just heading out for the day. If you can, try to arrange your seats so that you get off the plane faster and in queue before the other passengers on your flight, like you would if you had a tight connection.
3. Leaving the Airport: Once you are through all the checkpoints, make your way to the Heathrow Express train. This is a little pricier than other ways into the city, but only takes about 15 minutes to get you to Paddington Station. You can buy your tickets at the machines located just before the entrance.
4. Take the Tube: Once you arrive in Paddington Station, buy your tickets to get on the tube (you do have the option of buying an all day pass to save time as the lines can be long to buy tickets in some places). Here you can get on several tube lines. We got on the Bakerloo line to Waterloo, where you can get out and walk to the London Eye and across the bridge to the Palace of Westminster, Westminster Abbey, and St. James Park.
5. Plan your Sights: Since you won't have much time and there is so much to see and do in London, it's important to plan exactly what you want to see ahead of time! We had a few other things on our list, like the Tower Bridge, that we quickly realized we wouldn't have time for once we started to plan out our path. After you decide, use Google Maps to star the sights you want to see and find the tube stops closest to them so you don't waste any time trying to figure out where to go next once you're in the city!
6. Get back to the Airport: Be sure to leave yourself plenty of time to get back to the airport, as you will need to go back through security. We started heading back to the airport from the St. James Park area about 2.5 hours before our flight and had plenty of time, but that could change depending how how far you wander (and how easily you can get back to Paddington Station).
After all of that, we had about an hour to explore London, which was no where near enough time! I'm hoping I get to return soon and see much more of this city.