There is no district between Bergisch Gladbach and Cologne. Bergisch Gladbach is a town in the "Rheinisch-Bergischer Kreis". "Kreis" - literally translated circle - is comparable to the British county.
Cologne (the county is named after the city Cologne) is one of neighboring counties to the Rheinisch-Bergischer Kreis. The R-B K has a county twinning to Cumbria in England.
There are eight municipalities in the Rheinisch-Bergischer Kreis (sorted by size):
1. Bergisch Gladbach
2. Wermelskirchen
3. Leichlingen
4. Overath
5. Rösrath
6. Kürten
7. Burscheid
8. Odenthal
Maybe one of these names sounds familiar to you?
Edit: I don't think that gives an indication how she travelled to England. Distancewise, it does not really matter if you travel from there via one of the Dutch harbors, Bremen, Hamburg or one of the smaller German harbors.
Rossi