A coached track session at the old Whitchurch athletics stadium (now restored as a cycling centre) which is actually in Hengrove next door to Action Indoor Sports Centre, where there is parking (and the cycling centre obviously has places to lock bikes).

The address is Bamfield, Bristol, BS14 0FE

A video of the track:
https://www.youtube.com/watch?v=f_pUihnME9U

Directions:
https://www.google.co.uk/maps/place/Bristol+Family+Cycling+Centre/