You can only change your location autonomously (for a fee) in
1) London
2) South east
3) Scotland
4) West Midlands
5) North west
6) East Anglia
Where all other areas are concerned, you can just buy an advert for each location that you visit. This is what many of us now do.
Through a VS sales rep, it is possible to access the change of location facility for areas where you can't otherwise access it. This requires you to purchase all elements of your advertising, including the advert itself and including locations where the change of location facility is accessible autonomously,
through the rep. Note that in this scenario you are unable to either start or renew your advert on weekends or during public holidays since VS is closed then. Understand equally that buying any element of advertising autonomously automatically terminates your relationship with the sales rep (meaning, as you can see, the end of your access to the change of location facility).