A lot of foreign girls move location regularly because they are working illegally one way or another.
Many are trafficked and are regularly picked up and moved with no noticey their couriers in an attempt to disorient the girls and reduce their chances of escape. It also makes it harder for the police to get a handle on where they are.
EE girls who come here under their own steam usually don't pay the rates or utility bills when they become due so move when the debt collectors start arriving, leaving a pile of unpaid debts.
And a lot move because they wear out their welcome: service is crap, the local market gets burnt by the girls shit service and guys stop coming, so they move on.
Finally, some girls just use whoring as a way to go on a UK holiday tour