London Stansted Airport

If you look on Google Flights, you'll see that there are also frequent cheap flights to Luton and Gatwick airports. Why? Ryan Air and EasyJet are both discount airlines. Be careful to understand their fare conditions and baggage restrictions before booking.

All of the airports have their own website with sections devoted to detailed information on the various transport options. Taking trains is very easy, but which option is best for you depends on where in London your hotel is located. More than likely you will need a tube, bus or taxi from your arrival station to finally reach the hotel.

This would be amazing if it is an easy thing to do.

I can confirm it is an easy thing to do. If using EasyJet or Ryanair bear in mind that the baggage rules apply to you and there are no exceptions. I am always amazed at the number of people who think a refrigerator is an acceptable size for carry on luggage on budget airlines.

Yes, it’s very easy! The Stansted Express (train) goes directly to Liverpool Street Station in east London. If that’s not convenient for you you can take one of the many National Express buses that go to a variety of destinations from Stansted.

Going from Edinburgh to London I would only fly if it was a lot cheaper than the train (it definitely can be) as the overall time won’t be that different considering how early you have to arrive and getting to and from the airport on either end.

I just flew out of Luton airport a week ago. Took Thameslink to get there with my massive load of luggage from London Bridge station, nonstop. Easiest and most pleasant experience I've had in any English airport. (Edinburgh and Glasgow remain tops for the UK in my experience.) Still haven't experienced Stansted, but I'm sure I will very soon.

You say you want to go to Heathrow. The main line train from Stansted comes into Liverpool Street station which is on the Elizabeth Line high will take you directly to Heathrow.

I’m guessing that the cheaper flight is Stansted is on a budget airline vs British Airways flying to Heathrow. I’d suggest that you factor in the xtra train costs and, possibly, baggage charges before making a decision as it’s a lot less convenient to go to Stansted than to Heathrow direct.

As noted above, if you want to get to Heathrow from Stansted, the best way would be the train to Liverpool Street and then the Elizabeth line.

The train station is right in the airport at Stansted. If the above route has any issues another way to Heathrow would be take the train and get off at Tottenham Hale, then transfer to the Victoria Line and then swop to Piccadilly Line at Kings Cross or Green Park. Tottenham Hale station has had a major refurbishment recently and should be easy to navigate.

transfer to the Victoria Line and then swop to Piccadilly Line at Kings Cross or Green Park

It's a straight cross-platform change from the Victoria Line to Piccadilly Line at Finsbury Park too. If your destination is actually central London, the Stansted Express train to Liverpool Street Station is a fast and frequent service, and Liverpool Street is well connected on the tube to change for other destinations.

I'd probably add, I haven't considered flying from Edinburgh or Glasgow to London for years. The value of ending up at Kings Cross or Euston Station on the train outweighs any benefit of flying for me. Saves dealing with airports, and the transfer into central London from said airports.