So we are standing in the garden waiting to see the ISS to go over the top.
Lady asks, 'will we be able to hear it'
Theoretically you could hear it if you had a sensitive enough ear!
The ISS is stuck in a rather crap orbital altitude band due to the limitations of the dearly-departed Shuttle. Anything between 250 km and 1000 km is particulary draggy for a satellite.
At 400 km altitude, the air density is about a billionth of that at sea-level but its passage and the machinery noise still makes molecules vibrate.
If we knew the temperature of the atmosphere at that level ( I think it is quite warm ) we could calculate whether it is creating a sonic boom, too. Exceedingly weak but still..