French residents?Legal help needed please

[SuperLoudPoppingAction]

I don't have any idea what to do about this.
Property owned jointly in France by UK residents living in UK (married couple).
One died.
Apparently you have to lodge a 'declaration du succession' with the French government, with death certificate etc?
But I'm not sure where non-French nationals have to send this, or even of the correct form. I do understand 'normal' French but not legal French really nor all the different tax numbers/names for taxes etc

You could try posting this on one of the French Expat forums, such as French Entree, they are usually very helpful.
Or if you have a French notaire who was involved with the purchase?

Apparently he was unpleasant and there's no wish to re-engage him.
I'll have a look at French Entree - thank you for the suggestion.