Many moons ago the same happened to me, on a "test" flight to check out a GPS. We were too busy checking the thing out and flew right into the Luton Zone....
After I heard the controller call up a 737 about unknown traffic I woke up and checked and it was me...... So I volunteered my information and was told to call the controller on landing. I got an almighty outburst over the phone, I felt as tiny as never before and hated myself....
After that nothing happened, but I never forgot. It s a lesson, thats all, one you'll never forget.
Fly safe!