Magpie Pedro - was at WW that morning of your bust & was listening in to the phone/radio calls. If I remember rightly, you were one of two aircraft that LHR thought had infringed simultaneously ....
Interesting to hear the follow-up.
Can only comment as another PPL, but as someone who's done some mentoring, even when sitting right-seat & most definitely not PIC, I do my own pre-flight planning. Even for a local bimble.
I have a huge respect for instructors, since you have to be ready for the unexpected from the moment you approach the aircraft to the minute you sign in the paperwork. As a professional, it's the realising of the mistakes that defines what you do. Those who don't see it as a mistake are those that don't deserve the title. Some of the lessons can be hard.
Heathrow Director - who is no doubt the most pertinent person to speak on here - has already suggested this, but I would reiterate that Google Earth is a fantastic resource for pre-flight planning & I use it for every trip. When operating around a control zone like LHR's, it's a life-saver. A GPS is great, but there's nothing like having a mental image in your own head of what you should see when....especially in ratty conditions when you want to keep "head-up". I even print out 3D images of the view at the height I should be at given waypoints.
I'm currently looking at running a training course on GE for pilots with another PPL - if anyone's interested, let me know. Situational awareness is a very different thing to knowing how to operate the aircraft.
Hope the flying bug is still with you & the experience has let you grow rather than make you hang up the headset.
Flying is a privilege.
BFA