Is it permissible to offer the expiation for an oath (kaffarat al-yamin) in Jordan while residing in Britain, and should its value be calculated according to Jordan or Britain?

The expiation for an oath is feeding ten poor persons, or clothing them, or freeing a slave. If one cannot find [any of these], then it is fasting for three consecutive days. It is permissible to authorize charitable organizations to disburse the expiation as money, so that they may undertake the feeding or clothing, provided that the amount of the expiation is from the average of what a person feeds and clothes his family.