From the newsletter of St Giles Church, Imber, about three days ago:
"POSSIBLE CLOSURE OF ACCESS TO IMBER OVER EASTER 2024
The Defence Infrastructure Organisation (DIO) is responsible for access and safety on the Salisbury Plain Training Area (SPTA). We have been advised that we should inform anybody wanting to visit Imber and St Giles Church on the Easter weekend open days that there is a possibility Imber and, hence, St Giles will be closed to visitors for the Easter weekend. At present Imber and St Giles will be open between Saturday 30th March and Monday 1st April inclusive as planned, but heavy rain week commencing 25th March could alter the situation.
Please go to Our Web Site [google "St Giles Church Imber"] for Full Details There is information at the link regarding a road closure. Please keep looking back at the page for further information as it unfolds over the coming days."
Which roads are usable when there is access:
The road from Warminster, north of east to Gore Cross, is all tarmac (plus some water perhaps).
South to Heytesbury and north to Bratton: these each have a mile or so of gravel, otherwise tarmac.
But I haven't used them for a couple of years - may have been changed.