Horniman Staff have provided this programme of closures:

Area of the gardens to be closed
Closed from
For how long
Impact

Lower path which runs from Avenue towards wildlife garden
31st March to 16th April
2 weeks
Pedestrian entrance closed

Path at top of Avenue running towards Meadow Field
18th April to mid June
8 weeks
Only path linking the Museum area to west side of Gardens will be the one running parallel to the London Rd near the Avenue entrance

Outside Toilets
3rd May to mid June
6 weeks
Only toilets on site will be those in the Museum accessible from 9.30 to 17.30

North side of Meadow Field (at least half of the field). Ground source heat pump being installed
3rd May to 17th May
2 weeks
No access to pedestrian path which runs from Nods Way entrance towards sunken garden underneath the bandstand

Horniman Drive entrance down to the Avenue
Mid May to mid June
4 weeks
No access (vehicle and pedestrian) from Horniman Drive. Any vehicles accessing site will have to use London Rd entrance. Pedestrians will have to use Nods Way. Michael Horniman Building will not be accessible to vehicles.

What this says is that the Horniman Drive Gate will be closed to ALL vehicles and pedestrians (ie including Contractors) but this needs clarification.