Just nearest premises is at least something to work off.."5 minutes from the ALDI in Whereverville" etc.Depends which bit of the country you are in. Some forces apparently do not use grid refs and will only work from post codes or other location identifiers.
If you're ever in the Surrey Hills and need an ambulance having a list of postcodes for nearby roads is useful. Fortunately the only time we needed to do so there was a massive vineyard 10 minutes walk away.
If I took a call and all I could be provided with was that, I'd use the ALDI as locus and put further info on the log, officers likely to know the area and would still get to you.
If you are on a country road in absolute middle of nowhere, what3words would be handy. All I really have to worry about is sending it to correct town / city division N/S/E/W etc. If I knew you were on a road in middle of nowhere just out of North Whereverville...I could just send the log with location as unknown, and provide best descrption of location available- send to WRV-N etc.
Frequently happens with suicide cases- they dont really know, or care where they are- and often phone on 101 so no CLI location info.