Train travel from LHR

Firstly don't even think of picking up a car from Leeds Airport - as travelling there by public transport whilst not completely impossible is awkward and slow.

Why aren't you going by train a bit nearer to the Lake District than Manchester Airport?

Since you already at Heathrow, have you considered the options for flying onto a closer airport to pick up your hire car? As well as Manchester and Leeds/Bradford, you might consider Newcastle. The latter has the advantage that you can drive "along" Hadrian's Wall to reach the Lake District. Depends how much time you have, of course.

I see Enterprise and Avis offices near the train station at Kendal, or Windermere has a couple of local rental agencies that may require cars returned to the same place.

Did you have any previous post about this trip, where train options were discussed? The route sounds familiar.

Depending on where you want to be in the Lakes the closest airport could be Newcastle. But if your starting point is Heathrow and you want to go to a northern airport then flying is the way to go.

If you are determined to take a train I would allow four hours. If your flight is late and you miss the train then any pre-purchased Advance tickets are invalid.

Flying directly to Manchester or having a genuine connecting flight to an airport closer to the Lake District might have been easier, but it sounds with a specific time etc, that a flight just into Heathrow is booked already. A second, non connecting flight has much the same issues as the train; need to collect bags if any checked, risk of missing the flight if immigration lines are long etc

With things as they are at present I would agree that four hours after landing time would not be excessively cautious for a train from Euston. Even though if things go well there might be somewhat of a wait.

I usually rent cars from AutoEurope and was looking to pickup near the Lake District and drop off when we fly out from LHR
It did not look so far from either Manchester or Leeds, but sounds like maybe that is not the best plan
There is a great non stop into MAN from LHR, but not enough time from landing, customs/immigration, collecting bags, and so on
I will look into the the train closer to the Lake District and see if AE has locations
I thought that we would need 4 hrs, but needed confirmation
I am new to this site today, so I have not posted prior to this inquiry

We dropped a rental in Leeds at Avis. Wasn’t too challenging driving in. After dropping the car off we three walked a mile or so to the train station to rail into York. I looked at the Leeds/Bradford option and seemed a hassle. Your situation is the opposite to what we did but could work for you in a similarly sized city.