LHR is London Heathrow
LGW is London Gatwick
If you are required to make an airport transfer within the country, don’t forget to pick up your luggage from the baggage claim (Unless the ticket clerk said otherwise)! If not, you will go through the headaches of tracking it down and then wait for a couple of days for it to arrive. Make sure you know the final destination of where your luggage is going, and it should be to the final destination of where you are going. If it’s not to the final destination, and you are at the stop that requires you to pick up your luggage, pick it up. Keep that in mind so that you can do another self-check-in bag to your next final destination.
In my experience, I checked in my bag from DFW (Dallas/Fort Worth). My final destination was TIA (Tirana International Airport). The ticket clerk at the desk asked me where I was going and saw that I need to make multiple stops and a transfer. She informed me that I need to pick up my luggage at LHR, because I am making a transfer to a different airport in London, LGW. I learned that my luggage will not go directly to TIA, so I have to pick it up at LHR. I picked up my luggage at the baggage claim then moved to the next step. I need to get to Gatwick Airport. I took the coach bus to Gatwick, it costed me 25£ ($37), THAT’S FREAKING EXPENSIVE!!! The journey between LHR to LGW was about 90 minutes long. There are two terminals, north and south. Make sure you know which terminal you are going based on the airline you are flying with. If you happen to be at the wrong terminal, the shuttle will transport you to the other in two minutes. Easy.
The South terminal also serves the train station that takes you to London through Gatwick express.
The North terminal has some big shops and restaurants.
If you have long hours of layover, and wish to explore London to kill some time, keep in mind that taking the train from South terminal to London will take an hour and a half for both ways. If you have that much time and don’t mind spending that much money for such a short amount of time, go for it and make sure you are good with time managing. When I arrived at LHR, I had to wait about 40 minutes to cross the passport control. At LGW, going through security check could take longer when return to the airport. 9 hours layover is surprisingly not enough time to explore a lot in London because you have to wait to walk out of the plane, walk through UK passport control, waiting for your baggage at the baggage claim, the walking to the exit, the slow line purchasing of a ticket for the LGW transit, the transit from LHR to LGW, the baggage check in, the wait at the train, and the journey of the train, these took out a chunk of 3.5 hours of my layover (from my experience). So that leaves me barely an hour to explore. I had to wait for a train to South Terminal- 15 minutes wait, then another 1.5 hours back to the terminal, going through security check -10 minutes wait……wait…WTF, that was a quick and smooth security check out. I could have used another hour to explore London, but it’s better to be extra early to be on the safe side.
At Gatwick Express, where I bought my train ticket from South Terminal to London Victoria (London), that is the line where you will find most touristic sites, it cost me 16.50£ ($25) for an all day and round trip. The train leaves every 15 minutes but at this time, it was longer due to improvement works. It is also used as a pass so you can use it for the tube.