As I recall everything just stopped. I was at home, about to start my first year at uni. My parents had left the radio on in the kitchen and they announced a plane had crashed into the WTC- I thought it was an idiot in a cessna or something like that. So I turned on the telly and realised it wasn't. Dad (I think he was home sick) came in and we watched it. And I was having denial issues, I didn't want to believe that the things falling out of the windows were people, or the second aircraft was an airliner... People change - I guessed what 7/7 was as soon as it became apparent there were multiple explosions... didn't make it out of the house that day either.
11/7 I was in the National Archive and they announced there had been more terrorist attacks. We just looked at each other, shrugged, and went back to work.
Always remember, never surrender