Heathrow to Canterbury - buying tickets in advance?

There is a third route......

Take the Piccadilly line to Kings Cross/St. Pancras. Go upstairs and grab a train to Canterbury. This may not be the fastest way but probably the least expensive.

As for when to buy a ticket......that's the hard part. Normally, I'd say four hours to give yourself a little leeway but you never know.

What day of the week is this?

When you said Heathrow Express to Piccadilly that was probably a typo for Paddington- which is where the Heathrow Express goes to.

I guess your Option 2 would mean Elizabeth Line to Stratford International, then the High Speed train from there. I wonder why that route doesn't usually come up in the journey planners, which always suggest St Pancras- probably because that will be slower than St Pancras. Elizabeth Line trains from Heathrow don't go direct to Stratford (for Shenfield) from the May timetable change- they all go to Abbey Wood- so you would have to change somewhere in the Central area east of Paddington- the planners say Whitechapel, but anywhere would do. So that sounds a slightly odd route, if valid.

South Eastern say you can buy advance tickets for St Pancras to Canterbury up to 2359 the previous night. At 2300 I can still see advance tickets for tomorrow morning at £21.20, so that seems to be true. That suggests that, as soon as you know what time your plane is actually taking off (as opposed to it's ticketed time) you could take a reasonable punt and buy an advance ticket on your phone from St Pancras for 3 or 4 hours after landing.

To me personally the tube route all the way from Heathrow to King's Cross St Pancras is what I would choose, rather than any other (and there are several, which various people have suggested, I think we have 5 or 6 variations now from different people) requiring a change. The Tube route is only about 10 minutes slower than any of the routes involving the Elizabeth line.

One solution, if it works for you, is to build in an overnight to take care of any unexpected delays that might impact an advance purchase ticket. Travel as far as St. Pancras on arrival day. Check into a hotel near station, recover from flight, visit the British Library, or both. The next day travel to Canterbury. I recently did this because I had a few errands to run in London and I found I really enjoyed the travel break.

I am assuming (perhaps incorrectly) that you will be traveling to join RS Best of South England tour. If so, the taxi from the station to the hotel is less than 7 pounds and I would take it feather than pull luggage.

Take the Tube direct from Heathrow to St Pancras/Kings Cross.

Buy a ticket on the day at St Pancras to Canterbury West for £39.20 (after 10 am). No stress, job done.

Note that there is another possible route to Canterbury which I never see mentioned on here, but which may or may not be convenient. About £20 each and is walk up and go, no advance booking needed.
That is by National Express Coaches changing at Victoria Cross Station- the overall ride takes 4 to 5 hours. Departures are at 0450, 0710, 0820, 1010, 1110, 1440, 1535, 1700, 1820, 2025 and 0055.
The 0055 is direct and arrives at Canterbury at 0305. It has started from London Victoria and calls at CBS at 0040 before T5.
All these times are from Terminal 5 coach station but they all call at Central Bus Station 10 to 15 minutes later except the overnight service.

The other rail routes which are never discussed on this forum, either through lack of knowledge or an assumption that people just want the fastest route, is that Canterbury is also served by non high speed trains, direct from London Victoria, Charing Cross and Waterloo East stations- all easily accessible by tube from Heathrow- one change.

Thank you to Ramblin on for noting that you can buy tickets on the day. Another obsession on this forum is saving every possible nickel on train fares, concentrating on advance train fares.
At the end of the day, with what the plane fare costs, and what you are spending on hotels and restaurants, another £18 is neither here nor there. That principle applies to any journey from Heathrow. Any train ticket in the UK can be purchased on the day, and with all the uncertainties over international air travel that is the better option in many, if not most cases.

" is saving every possible nickel on train fares, concentrating on advance train fares."

We don't use Nickels in Blighty, so one can save them as much as you like - so, it ain't much use. Adavnce fares are a great way of travelling the the UK keeping costs to a minimum.

Thanks for all your help.

I double checked and our plane is scheduled to arrive at 1:20PM. We have a direct flight from Vancouver so it's possible that it will be on time. We land on a Tuesday, if that changes anything.

Can't do an overnight in London as I've already paid for a VRBO in Canterbury and we are anxious to see our daughter, which is why we are going there.

So if you're on time you might be out of Heathrow by about 2.30 pm, into St Pancras by 3.30 pm. Just getting the start of the evening commuter peak. The last train they even do advance fares on is at 3.37pm, then 7.37 pm after the peak. With a following wind (literally) across the Atlantic you might make the 3.37 train but you'd be reasonably lucky to do so.
Between 3.37 and 9.37 it's only the full £39.20 fare anyway.
So me, personally, I'd just go with the flow and buy the £39.20 fare at whatever time I got to St Pancras.
With luggage I might on my way out of the airport, knowing that I'm heading to peak hour trains, ask at the Nat Ex desk if there is space on the next Canterbury bus. If there was I'd take that, knowing I have a seat and that my luggage wasn't going to be a hassle on a crowded commuter train. Yes it's longer, but easier. The luggage is stowed under the bus.
Just my 2 cents thoughts (sorry 2 pence, lest I be criticised again) look at it.

There is another alternative you might want to consider and that is a car service. The train fares were cheaper, but the hassle factor was steep. There is nothing like having a private driver meet you in the terminal, wisk you to the car, and take you to Canterbury.

The driver we had drove quite safely, was most helpful loading our luggage, and commented on various things along the way. The car was clean, roomy, and well maintained. We would not hesitate to use the same service again. We've found that using a service based at the destination works well as they seem to know the best routes to take. The name of the service we used is Canterbury Airport Transfers. The web site (if my notes are correct) is taxicanterbury.co.uk/contact. The email is firstclasstravel@live.co.uk. Shoot them an email, outline you needs, and see what you think about their quote.