Big cities have residential areas on the outskirts, such as greater Glasgow having other councils and areas included in it. If I live in such an area, where is the border for travel that would impact whether I fast?
No impact on you where ever you live but when you travel, you should take the end of the boarder of the city or town where you live to start counting the distance of your travel. If you live in a big city which has suburbs, you start counting from the end of suburbs.
Wassalam.