For long distance intercontinental flights Heathrow dominates, the main alternative for flag carrier

In summary, traveling between Heathrow Airport and Harwich is a pain. Unless you give some time considering your options and make an informed choice of transfer it could well be a banana skin waiting for you to slip over.
In 2014, the only direct transfer option between Heathrow and Harwich is a taxi or private car. Pre-booked in advance a reliable operator of good standing should delta airlines flights charge below 200 British Pounds for a sedan/saloon size car for 2/3 people with luggage.
About half of the journey is on the M25 London orbital motorway, one of Europe\ s busiest and infamous for traffic congestion. During the working week add on another hour or more as a contingency in case of traffic delta airlines flights delays.
If the lowest delta airlines flights price is everything to you, then the cheapest way between Heathrow and Harwich is the London Underground between Heathrow Airport and London\ s Liverpool Street Station, then a train on to Harwich.
The cheapest (Oyster) fare between Heathrow and Liverpool Street is either 3 or 5 British Pounds depending on what time/day you travel. Travel time is about 70 minutes and you will need to change train at Holborn Station.
If you book on-line about 10 weeks in advance and pick-up your tickets at Liverpool Street then you may well get a discounted fare about 8 British Pounds (against delta airlines flights 31 British Pounds if you buy tickets on the day)
When a Royal Caribbean or Celebrity cruise ship is visiting Harwich, there is a special cruise train that runs one schedule in each direction between London\ s Liverpool Street Station and Harwich International Station, adjacent to the cruise and ferry terminal.
At a cost of 31.90 British Pounds per person in each direction this train runs non-stop and takes about 75 minutes. The actual train is exactly the same commuter style train that runs the hourly train service with a change of train at ManningTree.
The point to make about train transfer is that Liverpool Street Station is very inconvenient for most leisure travellers. A taxi will be at least 15 British pounds from the main hotel districts in London and there are no direct public transport links between Liverpool Street and Heathrow Airport.
There is also an hourly train service from Liverpool Street to Harwich with a change of train required. By buying tickets delta airlines flights on-line in advance and collecting them at Liverpool Street. Fares can be as low as 8 British Pounds. (The actual trains are identical to those used on the cruise train service)
For long distance intercontinental flights Heathrow dominates, the main alternative for flag carrier airlines is Gatwick Airport. However, if anything Gatwick is worse than Heathrow for Harwich transfers.
Stansted is dominated by low cost budget airlines flying to most countries in Europe, If you are flying from outside Europe, you may be able to fly indirect to Stansted via a European gateway like Dublin.
We are taking a cruise from Harwich May 26 on RCL Brilliance and are booked in to the holiday Inn Express T5 the night before. This hotel is not on the pick up list. Is it better to change the hotel and lose the 50GBP we paid or to take a taxi to the nearest delta airlines flights place where pick up will occur?