Train travel from York to Heathrow Airport

If I were you I'd cancel the last night in York and stay somewhere in London/environs convenient to getting to Heathrow. I would not want the stress of traveling that distance on the day of the flight because you have no control over any delays that could occur.

Giving the fact that you'd have to be at the airport by 11am and the more than likely event of a train delay, I would cancel my last night in York(hopefully you didn't prepay) and come back a day early. The stress saved is more than worth it.
I stayed at the Premier Inn Kings Cross and highly recommend it for one night.

I agree you should travel to London the previous day. I would not want to count on the train from York being on time. Plus, for an international flight you should arrive at Heathrow three hours ahead, not two.

We had an interesting experience the last time we traveled from York to London by train. We were supposed to be at our rented apartment at 2:00 to pick up keys and meet the owners, as well as greet my son and his family who were arriving around that time as well. The train we booked would have brought us to London by noon, with plenty of time to make our way to the apartment. But all trains heading south from York were held at the station due to a death on the tracks. Our scheduled train and several more were canceled entirely, and we were just told to take the "next one" once they started moving. It was chaos in the station as more and more people arrived and tried to find a way onto a train.

We eventually did manage to squeeze onto a train and find seats, and we arrived at Kings Cross around 1:00, just enough in time to take a taxi cross-town to meet the apartment owners at 2:00. Our son and his family arrived just ten minutes later. Fortunately we were there to welcome them and open the door.

All of which is simply to point out that things can go wrong with plans. Best get into London the day before, and not leave it to chance and on-time train journeys the day of your flight.

Thanks for your replies. We have an Airb&b in York and I canceled the last night and found a place in London. Out just a little money. Hated to do it, but couldn't take the gamble. Hopefully everything goes smoothly from here.

Mary

Definitely leave York Day early and spend your last night at a hotel near the airport then no anxiety about getting to the airport on time. Flying is stressful enough without adding worries about train delays.

Incidentally rather than changing from tube to train en route to Heathrow, you could just take the tube all the way from Kings Cross. The Piccadilly line goes direct to Heathrow from Kings Cross, no changes needed.

It can take a little longer (journey time around 50-60 minutes) but it saves an awful lot of faff at Paddington, especially when you've got luggage with you.

Okay.
The train from York to Kings Cross (not Crossing) should take two hours unless you are booked on an extremely slow train that stops everywhere. If so change it if you can

Secondly forget Paddington. Just get on the Picadilly Line tube at Kings Cross /St Pancras tube station and go directly to Heathrow, takes 50 minutes.

So 0700 - 0900 train York to Kings Cross. 10 minutes to get to the Picadilly Line. 50 minutes to LHR.

Add 20 minutes for wandering around lost. And that's about 3hrs 20.. You will be checking in by around 1030.