So in December I was originally going to park at the airport but I seem to have got a one way rental with hertz for Ł70 on the return which is slightly cheaper then the Ł80 on Just Park which also involves getting a bus in, so I am looking at getting a train to Heathrow.

I am planning on traveling from Milton Keynes and can get a train into central and switching to either Heathrow Express or the Elizabeth Line for a speedy transfer, what I cant work out is how the station is titled.

When I search a train as Heatrow Underground, It shows 59 mins needed to get from Euston to Heathrow. If I try doing Heathrow Train Station it adds Ł40 to book me a Heathrow Express where as splitting the journey its Ł10 the Express. I can't seem to see what combination or station the Elizabeth Line comes under to make sure I get the right ticket, as I could do MK to London Zones 1-6 aswell.

Any ideas how I can search to include, at the min, I seem to have found advanced train to Paddington is Ł9 plus Ł10 for HEX, Heathrow underground comes up as Ł21 but isnt time limited from MK.

Not answering any of the points you have raised, but another option is MK to Watford on the train, and then bus 724 from outside Watford station directly to Heathrow bus station. Might be worth considering.

Arriva bus 724 timetable

Elizabeth Line (Crossrail) and Heathrow Express use the same platforms at Heathrow, though different platforms at Paddington

Based on https://www.brfares.com/!fares?orig=MKC&dest=3081 there isn't a "not Heathrow Express" fare from Milton Keynes. So, you probably want to split-ticket in London, or ticket to London + oyster/contactless - should be Ł11.50 for Elizabeth Line from Paddington to Heathrow or Ł12.80 from Euston to Heathrow including the tube for the first bit

The MK + zones 1-6 travel card won’t cover the HEX but it will the Lizzie line and tube,

Easiest trips I can think of from Euston would be Northern Line to Tottenham Court Road then Lizzie to LHR (through running starts next month so no platform change at Paddington required) or Victoria line to Kings Cross then the Piccadilly to LHR from there.

Thank you, never actually thought about Watford, seems an hour on the bus which combined with a 20 min trip from MK, I think its almost the same as going into central and taking the train across. But a intresting option

From my testes on trainline I was able to see Heathrow Underground was the only one that didnt or if I went via London Zone 1-6.

I was thinking that but was unsure if the new line was considered part of zone 1-6 or a seperate? It seems London Zone 1-6 seems to cost around Ł6 as a advanced ticket or Ł15 as an off peak. Its flights in December so I think that would work out quite well. It seems there is not much time differance between HEX and Lizzie to LHR

I've been researching the exact same journey, and the answer is "it depends".

Its dependent on what time, and what day (weekday or weekend) you are leaving Milton Keynes; on which Heathrow terminal you are going to; on whether its a single or return journey; on whether you need flexibility on the return in case of late flight arrival; on whether you have a Railcard.

Cheapest is Ł6 Train Advance Single to Euston, then tube (Victoria Line to Green Park, then Piccadilly; or Northern Line to Leicester Square, then Piccadilly is faster than via Kings Cross) Ł5.50 single (contactless card) to Heathrow. Same on the return - but that's dependent on being able to find a Ł6 Advance Euston to Milton Keynes, and carries a risk if your flight is late.
If you wanted to take the Elizabeth line instead of the tube, the fare from Euston is Ł12.80 single to Heathrow. By December, the Elizabeth line will be through-running at Paddington, so the best way would be tube (Northern Line) from Euston to Tottenham Court Road, then Elizabeth line. Bear in mind the service pattern is every 30 minutes to Terminal 4, plus every 30 minutes to terminal 5, You may need to wait a while for a service to your terminal, so there's a decent probability you will not get there any faster than the 59 minutes on the tube.

Next up from Milton Keynes is the "Super Off-Peak Return" at Ł16.40 (Avanti only) / Ł16.60 (London NorthWestern only). This is valid for arrivals in Euston after 13:00 Mon-Fri, anytime Sat/Sun. Return on any train within a month but not valid from Euston 16:00-19:00 Mon-Fri.
Next is "Off-Peak Return" at Ł36 (after 09:30) Mon-Fri.
Next are peak fares, when things get expensive.

Thanks, I am guessing you are Oxford way based on your username

I am intending to do a single into the airport midweek in December, my return flight, I am going to drive with a car from Hertz, I have a provisonal booking for Ł70, realised I could do a points rental for Ł3.80 so might just do that.

I am not sure if your calculation includes the Ł12.80 in the advanced ticket or is an extra. If an extra you can avoid by simply choosing Milton Keynes to London Zone 1-6 when booking, on my search a return was Ł15.70 but that was not timed where as a fixed was Ł12.

Whatever you do, avoid Trainline. Prone to selling tickets for trains that don’t exist.

That's interesting. I use them a lot and have never had an issue but now I have put the kiss of death on that avenue of pleasure, what app do you suggest? I like a new travel app every now and then!

There is only a single reservation system for Great Britain, so if a train that will later be deleted from the timetable was showing as bookable on Trainline, it would also have been shown on all other booking sites. Blame the train operators for deleting trains at the last minute (if they delete a train by 10pm the day before it is scheduled to run, delay compensation is not payable based on the scheduled time of the deleted train).

Several train company booking sites are run by Trainline but just rebranded.

I use the LNER app but only because there has been a permanent 5-15% cashback offer on my Amexes and/or other cards since the start of 2022

I book via LNER at present because of various cash back offers. I used to switch around LNER / Avanti / GWR depending if there was a nectar bonus or not as well until they stopped the nectar link up.

I won’t use the train line because they charge a booking fee and why pay a fee when you can buy for free when booking via a train operator or at a station. They also wanted to charge a collection fee for using a station machine!

I normally book with the relevant operator - and if it’s multi then LNER for the aforementioned Amex benefits. Plus the app just works very nicely.

I follow a few railway people on the socials and they seem to have a disproportionate level of problems with Trainline bookings. Plus the booking fee when there is no need to pay!

Agree, avoid the Trainline like the plague. Book on the website of any of the train operators, preferably one that is involved in your planned journey.

Well trainline has to pay a fee to the operator of the ticket machine when you collect the ticket, and they don't own any ticket machines themselves which could receive the fee for dispensing tickets booked elsewhere.

In the past this fee was 40p per booking, so passing the charge onto the customer could be justified if the customer had the option to fulfil as eTicket. Though I believe it is now 0.5% with min 7.5p and max 50p. Although, since trainline charges their additional booking fee anyway, they should absorb any extra costs.

If you disliked a particular train operator, in the past you could cause them to lose money by booking any low value tickets with them and collecting at a machine operated by someone else, or even a ticket office as that used to cost 90p.

Is this the correct queue to join to moan about the SWR app not having biometric login? No? I'll just get me coat........