I do not know if such a list exists.
But load the full cap file https://feeds.meteoalarm.org/api/v1/warnings/feeds-united-kingdom f.i. in Firefox
it is a json file and FF expands it nicely.
That way i found Edinburugh
areaDesc "Edinburgh"
geocode 0
value "UK249"
valueName "EMMA_ID"
East Lothian" → UK245
You know the area names, so you can find the EMMA_ID’s
Wim