Flightpath was due over London at around 11:20pm last night according to the NASA website. Moving from South West to South East.
The International Space Station was visible around 10:08pm last night too.
Believe me, when you see it rise, you know it's not something coming out of Heathrow. And because of the angle of the sun, it appears to 'vanish' halfway across the sky as the Earth blocks out the light from the sun bouncing of its surface.
If it's not absolutely belting it down with rain tonight, you should be able to see them move across the sky again (and for the next few nights). Think they're due to have docked by then, so it will be one fastish moving white dot moving from South West to South East.