Upvote:1
Heathrow always takes longer than you expect. It's not just a matter of "arrive in gate A, jog to gate B". Even in the same terminal and without having to go through immigration, you will have to re-clear security and go through customs. While an hour is probably enough, a relatively short delay in your incoming flight would be enough to screw up your travel plans, leaving you in an international terminal without an onward ticket. You do not want to be in that situation.
Upvote:3
You seem to have answered your own question. You have to travel from your arrival gate to the border controls (which can be a 10 minute walk from some gates at terminal 2), pass through security (which could take half an hour or more if you are unlucky), and then sprint to your gate (which, again, could be a 10 minute walk away). Bearing in mind that boarding will close probably around 20 minutes before departure, you will need to do all this in around 30 minutes. If you are lucky and also a fast runner you will make it there just as they are about to close boarding. I would say you have a slim chance of making it. I would bet against you. My tip is that you should rebook your flight.
I tried entering your details into Heathrow's connection planner. They don't think you have a hope of making it, and suggest that you should contact your airline on arrival to rebook.