OK, so you will concentrate on London.... The Uber model will not work because if I am in London and the Uber driver is in Paris, I can hardly "teleport" the car and driver to London. The same applies to escorts and customers.
I believe a site is good but keep it local and good luck finding any escorts who do not have something dangling between their legs...
Using the Uber scenario. What is the point finding riders/customers when you have no cars.
My gut feeling is .... a bad business plan