Summarize this article in one sentence.
The National Express rivals the tube in its low price and is more comfortable and accommodating if you have a lot of luggage. It’s a full-size bus with air conditioning and bathrooms on board, and you won’t have to worry about being crowded as you would on the Underground. However, the National Express will have to deal with traffic if you’re traveling during peak hours. It also services other towns and cities before reaching Heathrow, meaning that it’s more likely to be off-schedule. Buying your ticket online from the National Express website reduces your stress on the platform and ensures that you get a seat on your bus. Online tickets range in cost depending on your departure time, but don’t go above £10.  Visit https://www.nationalexpress.com/en to book your ticket. Enter Heathrow and your terminal for the departure information, and London Victoria Station for your arrival. Book a departure time that’s at least 90 minutes after your flight’s scheduled arrival time. If you’re buying tickets at the last minute, head to the Central Coach Station between Terminals 2 and 3. You’ll be able to buy National Express tickets there, although the price might be higher than it is online. You can the Heathrow Express train, free of charge, from Terminals 4 and 5 to the Central Coach Station. Although the National Express does service Terminals 4 and 5, its lines hit the Central Bus Station between Terminals 2 and 3 more frequently. Busses will stop about every 15 minutes, making it the most convenient and time-saving option. The National Express also runs 24 hours a day on weekdays, and from about 4:00am-11pm on weekends. You can also wait for the bus a little longer at Terminal 4 or 5, or take the Heathrow Express train to the Central Coach Station for free. The National Express takes you directly to Victoria Station with no stops. From there, you can walk to your hotel, take a cab, or use the tube.  Your arrival time in London will depend on the traffic, so expect a slow journey if you’re going during peak hours in the morning or evening. You can transfer to the District Line or the Circle Line at Victoria Station.

Summary:
Take the National Express coach for a cheap, comfortable option. Book ahead of time online to guarantee a seat. Buy a ticket from the Heathrow Central Coach Station if you’re booking on the day of. Get on the bus at the Central Bus Station for the most frequent pick-ups. Get off the bus at Victoria Station in London.