How long to allow to catch through customs/immigration and catch a bus at Heathrow

It's really hard to say - it all depends upon whether (a) your flight arrives on time, and (b) how many other flights are arriving at that time. I've made it through in 45 minutes... and in over 2 hours - it really just depends - which of course isn't terribly helpful. However, given the early hour, there probably will not be a lot of other flights arriving. so if you are doing carry on only, you should be able to make the bus.

We've been through Heathrow six times. Remember to factor in the time it will take to walk from the customs exit area to wherever your bus is. We take the tube into the city most times and it can easily take 20-30 minutes to get there (we're old and walk slow).

There are any number of things that can make it very difficult or impossible to make. We learned long ago to relax and not overly stress ourselves on travel day. I'd just plan to catch the later bus and take my time getting through the airport. There are plenty of restaurants and shopping in the airport to easily spend a few hours. If the plane is late taking off, or facing unexpected headwinds, you'll be agonizing the entire flight worrying about it.

I used to fly to Finland with a connection in Stockholm for business and have a 100% record of missing the connection. The net result was waiting six hours or more for the next twice a day connection. I was a wreck the first trip, but learned to expect it and kick back in Stockholm or catch the next flight to Helsinki and spend the six hours waiting there.

I travel through Heathrow every summer and it can be a very busy place. At 6:35 am in the morning, there are usually several planes coming in from the US. There is usually a long line for passport control and depending on how many people are working booths that day - depends on how quickly you will get through. I would plan on at least 45 mins to get through passport control. If you are checking luggage then you will need time to go collect it (20 mins or more). I personally do not like to stress over a tight schedule. I would take my time and catch the later bus. Is it a National Express bus? if it is then you can pay a little more and get a flexible ticket for that day (if you flight is delayed you can catch a bus within a 12 hour window).

£5 extra each for 12 hours flexibility either side of your booked coach. Only you can decide whether you would value such an 'insurance' charge.

You haven't said which terminal you arrive at which also comes into the time equation.

Transportation is usually a matter of trading money for flexibility and time. Spend a few dollars and get the 12-hour tickets. Then you won't need to worry about things out of your control ruining the day.

National Express uses the central bus station at Heathrow, at terminals 2-3. If you arrive at another terminal, you'll need to factor in the time for travel between terminals.

Heathrow is busy, and early morning sees the arrival of the overnight flights from the U.S. east coast. Each dumps a few hundred people into the queues. Where you are in that queue is a matter of luck.

(Unless you get through passport control with unusual speed, your luggage should be off the plane and waiting for you, but it's gonna be sitting in a large area at baggage claim, so finding your bags won't be instantaneous.)

Thanks for all the responses. Sounds like we should book the later bus....and get the flex option

Thanks for all the responses. Sounds like we should book the later bus....and get the flex option

Good question! We arrive the same day @ 6:40 and I was wondering about reserving bus tickets to Oxford. Such great info! Thanks!!!

The coach to Oxford is a bit different as it is not National Express but 'the airline' operated by the Oxford Bus Company and is much more of a turn up and go operation being half-hourly.

Thanks, Marco!

When we used to travel regularly to London, I timed from the plane to the exit of the International Arrivals Hall. It took 45 minutes each time, even with seemingly long lines. Last time this was done regularly was around 2011/12. We arrived in the evening. Just an FYI. In March 2017, it took that amount of time or less.