Alan Harris is a Welsh playwright... (wikipedia)
Whether you could see it from the center of London is another matter.
Because of the nature of the orbit, we cannot predict thousands of years into the future for this object, but in anyone's lifetime now, there is no chance
Yesterday, we had a great rain storm for about 15 to 30 minutes, which helped matters a lot. However, today the rain is drying up and there is no more expected any time soon.
We really would need a transponder to improve tracking enough to firmly establish that an impact would occur.
That is, we would still not know better than one-chance-in-five whether the impact would really occur or not.
In a large telescope the motion would be perceptible against any stars in the field more or less in real time, sort of like watching the second hand on a clock, ... not quite that fast, but noticeable.
I think my mom used to wonder, 'What are you saying when you're saying that?'
However, to actually know what your seeing, a small telescope would be useful.