From the Association for Latin Liturgy website:
Entries are arranged in alphabetical order of English counties, but with the Greater London section placed at the beginning; Scotland and Ireland are at the end. We include all churches which we have been informed use Latin in the current Ordinary Form of the Mass.
The Directory may be viewed here or downloaded here.
The accuracy of the Directory depends upon reports by users. Please send these to enquiries@latin-liturgy.org