Plugging his draft elsets into Heavensat, it looks like the upper stage / satellite dispenser may be visible just below Venus at 19:50:50, rising to an altitude of 65 degrees in the south at 19:51:59 (these times are GMT and for Cheshire but should be close enough for most of the UK). The dispenser is supposed to start pushing them out around 10 minute after launch (ie out over the North Atlantic) but unclear what the separation may be by the time they rise above our horizon. Sky won’t be particularly dark so binoculars may help if the contrast is low.
Currently a little cloudy here but hopefully someone sees something.
Good Luck, William