A better suggestion - use the location reported by the phone
When you call the emergency number, your phone transmits your location at the same time, and it's free, and the mobile network provides a location too (presumably based on cell tower triangulation)
https://eena.org/our-work/eena-special-focus/advanced-mobile-location/
> AML stands for Advanced Mobile Location. In the event of an emergency call, an AML-enabled smartphone (all Android and iOS devices worldwide) automatically sends accurate location information of the caller to the emergency services. This information is derived from the location data of the phone (GNSS, Wifi).
> AML is not an app; it does not require any action from the caller. AML is simply a protocol to transport the data (using SMS and/or HTTPS) from the smartphone to the emergency call centre. AML is – of course – free of charge. Emergency services are then able to receive this information in all the countries that have deployed AML.
https://eena.org/knowledge-hub/documents/aml-in-the-united-kingdom/
> Handset locations obtained through the AML functionality are be compared to the location provided by mobile networks (using cell coverage information), using an algorithm that analyses factors such as time of positioning and the separation of the two locations.
> Once the mobile handset knows its location it is sent to BT using a simple, already available, Short Message Service (SMS) based protocol (which gives 160 characters of data).
If you don't know where you are and your phone isn't able to use GPS to locate you, W3W is going to be just as bad as AML.