London Underground Heathrow To London, Times & Prices
Harwich
The downside is crowded carriages and around 20 stations into town. There will be an Underground station near your ultimate destination, (after perhaps a change).
Heathrow Airport is in Zone 6 of London's zoned transport system. (To understand the zone system which is the basis for  all fares on the London Underground, read our using the London Underground page).
The  Underground carriages become grossly overcrowded during peak rush hours. Heathrow is first stop so you will get a seat, getting off in Central London with lots of luggage at this time maybe an experience you can do without after a long flight.
3 Heathrow Underground Stations, 4 Heathrow Passenger Terminals
Heathrow Airport has three Underground stations for the four passenger terminals. All trains visit the Heathrow Central Station that is for Terminals 2 and 3, some trains go to Terminal 4, the rest go to Terminal 5, no train visits Terminal 4 and 5. When you are returning to Heathrow make sure you board the right train.
Heathrow Airport
Night Tube   Map
Route 1 (Terminal 4) - Incoming trains from London will branch off after  Hatton Cross station to Terminal 4. After Terminal 4 the train  loops around to Central (Terminals 2,3) before going back to London. These trains do not go to Terminal 5 and do not travel the other  way from Central to Terminal 4.
Route 2 (Terminal 5) - Incoming trains from London will go straight   to Central (Terminals 2,3) before going onto Terminal where the train terminates. After a short while the train will return  to London the same way. These trains do not visit Terminal 4.
Train  Times & Journey Planning
The  first train to Central London leaves Heathrow at around 5.10 a.m. , (30 minutes later on Sundays). The last train leaves for Central London around 23:45 (15 minutes earlier on Sundays).
The first train from Central London arrives at Heathrow at around   06:40 and the last train leaves for Heathrow from London around 00:20 (23:30 on Sundays).
On Fridays and Saturday nights the Piccadilly Line runs all night at around 10 minute intervals between Terminal 5 and Cockfosters, stopping at Heathrow Central for Terminals 2 and 3. No trains run to Terminal 4 as part of the night service and if you are interconnecting to reach your destination, check that the other line also runs a night service, (see Night Tube Map link within the sub-menu above).
When the Underground is shut there is a night bus alternative, route N9 which runs throughout the night at 30 minute intervals from Terminal 5 and also visiting the central bus station where Terminals 2 and 3 are. The route includes stops at Hammersmith, Knightsbridge, Hyde Park Corner and Piccadilly.
Changing Trains From The Piccadilly Line
Although the Piccadilly Line goes direct to many of London's major hotel districts a good proportion of travellers will need to change Underground train onto a different line. The most common change is to switch to one of the District Lines trains or to be going to Victoria, a major hotel district. If you look at the Underground Map, stations like Earls Court, South Kensington or Green Park look good places to switch.
In practise, these stations are not such a great idea towing luggage as the distance between lines is significant and you will have to negotiate steps, escalators etc.
Hammersmith and Barons Court are better stations as both lines use the same platform, you just walk off one train and the other train is about 8 yards in front of you. Even if you are taking the District Line branch down to the Bayswater/Paddington hotel area it pays with luggage to change at both Barons Court and Earls Court where trains depart from the same platform than battling the crowds and obstacles from the Piccadilly Line deep Underground at this point to the District Line on the surface.
London Underground Night Service - The Night Tube
In 2016 the London Underground begun to introduce a full 24 x 7 service on Friday and Saturday nights only. Introduction has been on a phased basis.
Night Tube services are now running on the Central, Victoria,  Jubilee line,  Northern line (Charing Cross branch) and Piccadilly line (but not Acton to Uxbridge branch). The Night Tube will offer a 24-hour service on Fridays and Saturdays.
Standard off-peak fares are levied for travelling on the Night Tube using Oyster and Contactless Cards.
Travelcards are valid from the first day of issue (using the date printed on the card), and for journeys starting before 04:30 the following day. For example, if you buy a 1 Day Travelcard at 11:00 on Friday, you can use it until 04:29 on the following Saturday.
Taking Luggage On The Underground
Interior of Piccadilly Line Carriage
The London Underground system is bustling and crowded at all times of the day. This is not a problem normally, but using the Underground with luggage in tow is it practical?. Well the good news is yes it is fine, and many people do use the London Underground routinely with luggage.
The caveat is within reason, its not such a good idea if you have arrived on a flight with a North American flight's luggage allowance. Up to one case of about 20 kg (44 lbs) should be fine. The main thing is to be prepared. Its not going to be a pleasant experience unless you're travelling early morning on a Saturday or Sunday, just think of the money you are saving.
At Heathrow Airport, the Underground trains are near empty as they start at Heathrow, crowding is not going to be a problem at this point. You can do yourself a big favour by getting as far as possible away from other passengers with luggage on the platform before boarding. By the time you get to Hammersmith the probability is that people will be standing and the carriages are getting crowded.
So the trick is to put your luggage in the space by the door and sit in an empty seat next to it so you can keep an eye on it, (see images). Now you see the reason why you want to get as far from others with luggage on the platform. If the train gets really crowded a lot of people prefer to stand and sit or lean on their luggage.
Getting The Best Fares On The Underground
For the vast majority of people using the Underground purchasing a cash ticket on the day is very expensive compared with the alternatives everybody else will be using.
Yes, it can be complicated, especially if you have kids, but if you spend a little time understanding the basics you will be rewarded handsomely financially by purchasing the appropriate ticket for you.
For the  majority of visitors an Oyster Card for each person will be the core of your transport needs within London. You can buy on-demand on arrival at Heathrow at the Underground Stations or you can buy in advance on-line a special Visitors Oyster Card.
The Oyster page linked below will enable you to budget likely costs, explains the advantages and disadvantages of standard Oysters v Visitor Oysters and potential money saving additions like Travelcards if you are staying more than 5 days and of course the hoops you need to negotiate if you have kids, (under 16 years of age).