gonna have to second steffi on this one:
whilst i appreciate it was beneficial for you during your interview process, making a general sweeping statement that it is possible for all to visit Heathrow tower is likely not the best idea.
I dont know whether you had to wait a long time for the ID to be issued at the ID centre, but that can be an absolute pain at the best of times, even where the building is now by the Queens building. So when they imminently move it to Heathrow house which is miles away... exponentially worse. I remember the wait when i was getting my airside pass for work
The amount of time it takes the person escorting the visitor as well, the length of the walk through the terminal is bad enough twice a day, let alone 4 times...
To alleviate any misconceptions, I dont have a problem with people visiting up here, I just think the strain it puts on the person dealing with them when they have loads of work on their plate already is unnecessary. By all means visit towers and centres during application, but maybe try and pick landside towers to keep it easy for everyone. If and when you get to college, I know my watch management are more than happy to welcome college visitors on weekend afternoon shifts, I myself was a beneficiary of this a while back. Also in terms of learning this may well be a better time to visit as you understand more of whats going on.
I appreciate when people think of a tower to visit, Heathrow is likely one of the first if you live in or around London. But its not as easy as your post seems to imply, far from it...